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Magnetic Susceptibility: Instrumentation and Analytical Applications Including Bioscience L. N. Mulay” and Indumati L. Mulay Department of Materials Science and Engineering, 139 Materials Research Laboratoty, The Pennsylvania State University, University Park, Pennsylvania 76802
PROLOGUE At the outset, we would like to join myriads of magneticists in paying a tribute to Professor John H. Van Vleck of Harvard University, who was awarded the 1977 Nobel Prize in physics, along with two other physicists. Professor Van Vleck received this highest honor, which in our opinion was long overdue for many outstanding contributions, which included especially his contributions t o the modern theories of magnetism. His 1932 classic work (90) on “The Theory of Electric and Magnetic Susceptibilities” indeed laid the foundations of the prolific and ever-growing research on magnetic susceptibility, a small fragment of which is reviewed here. In this ninth review on magnetic susceptibility, we survey important trends in instrumentation and applications, especially in the realm of analytical chemistry including bioscience. T h e first eight reviews appeared during 1962 to 1976 (47a, 55-61). This 1978 edition covers literature from about January 1975 t o December 1977. In response to an editorial plea, we have made this review more concise than the previous ones. In doing so, it seemed imperative that we depict the exceptionally novel trends in the instrumentation and applications area and eliminate some that we covered before, without, of course, implying in the least that these are no longer important. Hence, we shall not review the work on lunar Sam les, which was adequately covered before (58,59). It should {e noted that new books by Mulay and Boudreaux (48a,b)and excellent surveys on the transition metal and rare earth complexes are published by the Chemical Society, London. Since this review is concerned with instrumentation and analytical applications, we have focused relatively more attention on practical aspects of instrumentation and have attempted to point out the truly new trends in the hope that experimentalists will explore novel avenues of instrumentation for specific problem-oriented research and that they will not remain chained to otherwise outmoded techniques. Since classical methods, such as the Faraday and the Gouy techniques, quite surprisingly, continue to be very reliable for the measurement of weak susceptibilities and since these are relatively less expensive than some of the modern gadgetry, we shall continue to incorporate important modifications and tricks-of-the-trade reported by ingenious workers. Unfortunately because of limitations of space, we shall not be able t o survey various temperature controlling and measurement devices; however, we shall discuss thermometric errors, etc., encountered during magnetic measurements. Furthermore, while curtailing our usual coverage of the general field of instrumentation, we have stressed applications which are expected to be of special appeal to analytical chemists. Since structural analysis is an important aspect of analytical chemistry, we have included typical examples of such analysis. This was also done in response to requests from our readers. Our rationale for selecting these areas is given later under the “Applications” section. We urge our readers to refer to our earlier reviews (56-60) concerning the scope of areas such as solid state science (that is, chemistry and physics of solids), which is synonymous with materials science and materials engineering in order to appreciate their interdisciplinary role in science and technology, and to appreciate the relevance of these areas to societal needs and their relationship to analytical chemistry, with special reference t o the characterization of materials a t the macro- and microscopic levels. I t should be noted that a few developments in instrumentation and their applications are reviewed under the 0003-2700/78/0350-274RSOI OO/O
section on “Applications”. See for example Mulay e t al. (62), Philo (71),Munday (65), and Sheinin (77).
GENERAL LITERATURE Abstract Services and New Journals. References should be made t o our earlier reviews (55-61) concerning abstract services. Monographs, Books, Contributed Chapters, and Reviews. A Wiley-Interscience (1966) monograph on “Magnetic Susceptibility’‘ written by one of us (L.N.M.) which was unavailable for some time has now been made available by the Krieger (Wiley) Co. (47b). Chih-Wen Chen (15) has a book on “Magnetism and Metallurgy of Soft Magnetic Materials”. It should be noted that the terms “soft” and “hard” used in this context refer to the “ease” and “hardness” of magnetizing (and demagnetizing) certain technologically important materials. Permanent magnet materials such as barium ferrite and alloys such as SmCoj generally fall in the latter category and are said to have a high “B x H” or (magnetic) energy product. Another book on the magnetism of metals by Pekolski (70) and a review by Taylor (88) on this topic have been published recently. A book edited by Parks (68) offers the first and only comprehensive treatment of a new research area in chemical physics, namely the mixed-valence phenomena. T h e book presents experimental evidence (including especially magnetic susceptibility studies) of valence fluctuations and related many-body phenomena in an enormous number of substances, as well as a wide variety of methods and techniques for their investigation. While these phenomena remain largely unexplained, many of the theoretical contributions indicate fruitful directions for future research. The field, though still in its infancy, is rapidly growing and promises to have wide and significant applications. Chemists and chemical engineers in the fuel industry (note that most good catalysts are mixed valent) and solid-state electronics engineers developing new classes of narrow band devices will find this book t o be an excellent introduction to, and overview of, a field that will soon have a great impact in these areas. Another forthcoming book by Huang and Chu (31)discusses several aspects of mixed and fluctuating valence phenomena, elucidated via magnetic susceptibility and related techniques. Weber’s book (96) on “Superconductors” and Nobel Laureate Dirac’s book (19) on “Spinors” (describing the behavior of magnetic spin ’/* particles-the fermions) should prove useful, respectively, to those engaged in superconductivity research and in theoretical aspects of magnetism. Books on “Molecular Diamagnetism” and “Molecular Paramagnetism” by Mulay and Boudreaux (48a,b)appeared in late 1976. The “Diamagnetism” title contains three chapters (by L.N.M.) dealing with the general realm of diamagnetism, recent advances, and definitions and units. In addition, Mulay gives selected applications of magnetism and magnetic materials such as the superconducting alloys, which are expected to provide answers to negligible energy consumption, high speed mass-transit systems. Cressy and Hameka have outlined the theories of diamagnetism whereas Haberditzl gives a n encyclopedic survey of various chemical applications of diamagnetism. T h e “Paramagnetism” title similarly contains chapters by Mulay describing magnetic phenomena, magnetic ordering, magnetic applications, recent advances, definitions and units, whereas the theories of transition metal complexes, behavior of d” ions, lanthanide ‘F 1978 American Chemical Society
ANALYTICAL CHEMISTRY, VOL 50, NO. 5, APRIL 1978
L. N. Mulay is a professor of Solid State Science in the Materials Science and Engineering Department at The Pennsylvania State University since 1967 and served as chairman of the corresponding interdisciplinary program from 1967-1972. He took his P h D (1950) in physical chemistry from the University of Bombay. He held various research and teaching positions in chemistry at Northwestern and Harvard Universities before joining the facum at Penn State in 1963 as an Associate Professor. Dr. Mulay is the author of over 130 research publications and a monograph on “Magnetic Susceptibility”, He is the co-editor of two new treatises on the “Theory and Applications of Molecular Diamagnetism and Paramagnetism” (Wiiey. New York, N.Y., 1976). He is internationally recognized for his many contributions to magnetics. His research interests have centered on magnetic probes, such as susceptibility, broad-line NMR, EPR, and Mossbauer spectroscopy for the characterization and structural elucidation of solids at the macro and microscopic levels. Dr. Mulay has traveled widely and contributed to international meetings and research conferences He is a member of several professional organizations and was chairman of the Central Pennsylvania Section of the ACS (1965). He has been a regular contributor to ANALYTICAL CHEMISTRY’S Fundamental Review issue since 1962. ~~
Ms. Indurnail L. Mulay has been a research associate and collaborator in the Materials Research Laboratory at he Pennsybanla State University since 1963 She received a B S in chemistry and M S in biochemistry (1953) from the Universitv of Bombav She also earned an M S (Radcliffe College) in 1957 and a Ph D in biology (Cincinnati) and did postdoctoral research at the Universty of Cincinnati before joining Penn State Her main research interests include radlaton genetics, trace metal analysis. EPR studies on cancer tissues, and the effect of magnetic fields on biological “ 6 matter She has published several papers and i reviews in these areas and contributed a chapter to a book on biomagnetism She is a member of several professional CHEMISTRY s organizations She has been a regular contributor to ANALYTICAL biennial Fundamental Reviews since 1964
and actinide compounds, etc. are extensively treated by Casey and Mitra with a theoretical chapter by Siddall on the La and Ac compounds. Of special interest is Hatfield’s contribution on condensed (i.e., cluster type) compounds which (according to a relatively old system of nomenclature) are said to show “intramolecular” antiferromagnetism. The general philosophy of the two volumes as explained in Mulay’s preface to the two books was given in our 1976 review (61). An extensive book on the physics of magnetism, which may be regarded as a “treatise” in the form of a n English translation of Vonsovskii’s (94)well known 1971 Russian text is now available. In addition t o discussing the magnetic properties of ions in insulators (ionic and molecular compounds) and basic theories, he discusses properties of metals, alloys, semiconducting and superconducting materials, and magneto-optical, thermomagnetic, and glavanomagnetic phenomena of interest to materials scientists. Books by Foner (22) and by Weiss and Witte (97) should be of interest to magnetophysicists and magnetochemists. Levy et al. (40) discuss “Amorphous Magnetism”. Weissbluth (98) presents a review of principles of paramagnetism and electron paramagnetic resonance (EPR) spectroscopy and of magnetic studies on the derivatives of hemoglobin and myoglobin. An excellent review by Gallop and Petley (23) on the “Superconducting Quantum Interference Device(s)” with the acronym “SQUID” and their multifarious applications should be of special interest to magneticists. In addition to describing magnetic susceptibility measurement, the authors discuss geophysical applications, measurement of magnetic field gradients as applied to magnetocardiography (MCG) and magnetoencephalography. Their review of earlier work shows that MCG gives more detailed information on heartbeats than electrocardiograms (ECG) and that SQUIDS are capable of recording the a-rhythms of brains and so on. Another book by Geddes and Baker (25) should also be consulted. The
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applications of Josephson junctions (SQUIDS) t? magnetic measurements have been surveyed by Clark (17) in a review with 74 references. Other topics include memory cells, latching logic elements, nonlatching devices, the flux shuttle, and the use of dc and radiofrequency superconducting quantum interference devices to measure magnetic field, magnetic field gradient, and magnetic susceptibility. Cryogenic technique at and below 4.2 K and its application t o materials research have been surveyed by Erdmann (20). A review with 528 references is given on cryostats, thermometers, low-temperature production, refrigerators, measurement of electrical and thermal conductivity, heat capacity, elastic constants, thermal expansion, and plastic properties, high-pressure apparatus, measurements on superconductors, measurement of magnetic susceptibility and the Mossbauer effect, optical methods, and the Helium I1 quenching experiments. A review containing 11 references on the synthesis and magnetic properties of glasses based on boron oxide (B203) is given by Zaveta (99),whereas the work on the possibility of antiferromagnetic ordering in amorphous systems is reviewed (31 references) by Simpson (83). An interesting review on the magnetic susceptibility of the soil and its significance in soil science is given by Mullins (64) with special reference to ferrimagnetic minerals such as maghemite (y-FezO3), magnetite (Fe,O,), and titanomagnetites. Magnetic properties of poly P-diketonate complexes have been also reviewed by Glick and Lintvedt (26). S.I. Units in Magnetism. The adoption of the Systemme International (S.1.) units in all areas of science, including magnetism has attracted the attention of several authors including Mulay (cf. 48). Despite recommendations and urgent pleas t o adopt this new rationalized MKS system of units, many authors find it easier t o adhere to the old unrationalized Gaussian cgs-emu system. Mulay (cf. 48) has recently discussed the S.I. units in magnetics and the conversion factors for the above Gaussian to S.I. units and vice versa. Chiswell and Grigg (16) also discuss the rationale for the adoption of S.I. units, rules for their use, and give extensive tables of S.I. units for physical quantities, engineering units, and symbols. Elarlier authoritative and rigorous mathematical developments pertaining to the S.I. units are given by Jackson (32). Schneider (78)gives a review of S.I. in scientific instruments and tables for S.I. units. In our opinion, the S.I. units will not be adopted by the entire scientific community, unless the editors of scientific periodicals, publishers of books, reports, and the like and professional scientific organizations mandate their adoption. In our present review, we have quoted various magnetic parameters as originally reported by the authors in the S.I. or the “cgs-emu” units. Reference should be made to standard tables (cf. 48) for the interconversion of the two systems of units.
INSTRUMENTATION Sensitivities of the Force, and Vibrating Sample Magnetometers. Lewis‘s letter (41) gives an enlightening comparison of the force magnetometer (FM) of the Faraday balance type using the Lewis gradient coils and the Vibrating Sample Magnetometer (VSM) designed by F’oner (21) and available from commercial manufacturers. Furthermore, Lewis offers comments on Reeves’s (73) alternating force magnetometer (AFM). These magnetometers have been appropriately reviewed by us in the past (55-61). Foner (21) has in turn offered comments on Lewis’s letter (41),to which a detailed reference will be made later. These articles would be informative and indeed very useful to all experimental magneticists and especially to our new (and uninitiated) readers in buying and constructing one or more of such magnetometers for specialized investigations. In the following discussion, we consider essentially the question of defining and quoting the sensitivities of magnetometers. With regard to the sensitivity of VSM’s (and particularly those that are now commercially available), Lewis (41)points out that “If the sensitivity of interest is magnetic moment (or magnetic susceptibility) per gram of a substance, then the sensitivity of a particular configuration [of the detector coils] depends on the density and size of sample that can be accommodated. Sufficient clearance must be left between the vibrating sample and detecting coils to prevent the sample
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vibration t o the coils.” Lewis then shows that [even] for an idealized situation a n apparent sensitivity for magnetic emu/g-Oe would be susceptibility quoted as “Ax N wrong and indeed misleading because a density of more than 100 g cm3 [!I would be required for the sample in order for it to it inside his [Foner’s] detecting coils”. The [idealized] situation considered entails the following parameters: 0.5-mm clearance [between the vibrating sample and the detector coils], a cylindrical sample 1-mm 0.d. and 3 mm long, a density [of say] 1 g/cm3 which gives a noise level of 3 X emu a t a field of 10000 Oersteds corresponding to a sensitivity of 1 X lo+ emu/g for magnetic moment per gram of sample, which corresponds to a sensitivity of 1 x emu/g-0e for magnetic susceptibility a t lo4 Oersteds giving [as stated before] a sensitivity of A x emu/g-0e. Our readers should note that the term “magnetic moment“ used by Lewis-FonerReeves et al. and by most physicists and/or electrical engineers corresponds to the magnetization M defined in terms of atomic moments [M = gpJB,] where the symbols have their usual meaning. [See for example, Smart (85),Boudreaux and Mulay (486) for the basic definition of M arrived in terms of the Brillouin or the Langevin-Debye formulation of paramagnetic magnetization (and magnetic susceptibility)]. T h e readers should also note that some of the information in square brackets including the sign of exclamation [!I introduced in Lewis’s (41) quotes was inserted by us to paraphrase more effectively the import of Lewis’s arguments. Foner in his reply (21) states the following: (i) “The moment sensitivity is unambiguous and is better than that reported to date for any other method (including superconducting devices)”. (ii) “The statement that a given moment would correspond t o a susceptibility for a 1-g sample a t lo4 G (1 Tesla) permits the reader to be assured about the units (and that the terms moment and susceptibility have not been confused and that mass, not volume susceptibility is being discussed)”. (iii) “By stating the sensitivity in magnetic moment the reader has all he needs to convert to x in appropriate units at various fields”. In our opinion the choice of expressing the sensitivity of any magnetometer in terms of (i) the mass susceptibility (x) or (ii) magnetic moment (M)is indeed very difficult and poses vexing problems, just as unsurmountable as the problems encountered in choosing between the Gaussian (cgs-emu) system of units vs. the new S.I. units. In any event, it would be desirable if writers and especially manufacturers of commercial magnetometers would (i) refrain from quoting “susceptibility sensitivity” which a t first glance would appear exaggerated, or otherwise misleading, and (ii) to refrain from stating that “changes in susceptibility as small as “SO many units” can be detected”. Most magneticists are generally interested in accurately measuring the absolute magnitude (and the sign, + or -) of magnetic susceptibility (or “moment”) and in measuring the changes in susceptibility (or “moment”). Indeed we all must expect a n d respect t r u t h in “advertisement”. V i b r a t i n g S a m p l e (V.S.) Magnetometers. Bragg and Seehra ( 7 ) report a rigorous mathematical analysis of induced E M F in vibrating sample (V.S.) magnetometers. Their analysis in conjunction with Guy’s evaluation (28) given later should prove extremely useful to experimentalists interested in building 3 sensitivit V.S. magnetometer. Readers should also refer t o a n earlier section on the “Sensitivity of Magnetometers”. Assuming a point magnetic dipole sample, located in a general position with respect to a single-turn circular pickup coil, the instantaneous flux cutting the coil and the induced E M F due t o sample motion were found t o be linear combinations of elliptic integrals of the first and second kind. An alternative representation of the flux by a power series is also given. Their ( 7 )results can be applied to arbitrary versions of magnetometers by specifying coil size and sample position and orientation. Four popular designs including the Foner system (21) and the one used by the authors are considered. The numerical computations were done using parameters from some known experimental systems. T h e good agreement between the form of the calculated and observed outputs in two of the four systems suggests that the assumptions made in the calculations are perhaps valid under typical experimental conditions. If the sample is nonspherical and its size
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is comparable to the sample-coil separation, then corrections to the dipole approximation are said to be necessary. It should be noted that the calculations were done for a single-turn coil of fixed radius and a single separation from the dipole. In practice, coils consisting of several hundred turns, all of which may not be at the same distance from the sample at a given time, are used. Although it would seem to be possible to calculate the effect of these variations in a given situation, the authors point out that the good agreement between the form of the theoretical output for a single turn and experimental output from the first two multiturn systems suggests that these variations do not play a major role. Consequently the authors have expressed a hope t h a t their “exact” calculations would be useful for designing magnetometers and for optimizing these designs. Guy (28a) gives the following critique of the above paper by Bragg and Seehra: “Although their paper is welcome for its rigorous approach to the problem of the theoretical E M F obtainable from pickup coils used in vibrating sample magnetometers, it is incomplete since it does not pinpoint the crucial factors governing coil pickup efficiency. In addition, these authors (Bragg and Seehra) make some statements which would be misleading to the uninitiated and thus require further comment.” In this letter an attempt is made to clear up these shortcomings and demonstrate a n extremely simple approach to coil design which follows directly from a little quoted paper by Mallinson (45). If detailed agreement between empirical results and calculated EMFs is required (Le., an absolute calibration), then it is essential to make the calculation for thick coils and finite specimens. The differences between this calculation and that shown by Bragg and Seehra are both quantitative and qualitative [Guy (28)],since the sample position for maximum output changes with sample length and coil thickness. If an optimization of coil design is required, then this can be accomplished, to the same degree of qualitative accuracy as that obtained by Bragg and Seehra, more simply by the use of a reciprocity theorem of electromagnetism and, if necessary, suitable two-dimensional models which are exactly soluble [Mallinson ( 4 5 ) ,Guy (28a)I. The design of efficient pickup systems, quite apart from a need for an optimization of coil geometry, requires the strict observation of two rules. (i) The effective turn area of the coil system presented t o external fields must be as near to zero as possible. System 1 described by Bragg and Seehra ( 7 ) would be highly impractical since in all normal circumstances 5 0 - H ~pickup would swamp any sample signals making even lock-in detection very difficult. (ii) T h e coils must not vibrate with respect to the applied magnetic field. Generally this requires that the coils be extremely well isolated from the mechanical vibration of the sample or that they are rigidly attached to the source of the magnetic field [i.e., the pole face of an electromagnet or the coil former of a solenoid-see Foner (211, Sprinpford et al. (cf. 28), Guy (28a)I. After rules i and ii have been satisfied. Dossible coil geometries can be optimized for maximum pickip and minim& sensitivity to sample position. In the rest of the paper, Guy (28a) analyzes various equations derived by Bragg and Seehra ( 7 ) and points out that for particular sample positions, pure second harmonic signals are produced and that for general positions a mixture of the fundamental and harmonic frequencies is produced. This is said to be responsible for the apparently anomalous dependence of peak output on vibration amplitudes reported by Bragg and Seehra. We urge our readers to refer to the papers cited above for a thorough understanding of the workings and problems encountered in the construction and operation of V.S. magnetometers. is A new and refreshing approach in the design of V.S.M. described bv Guv 128b) who uses the “freauencv doubling” effect. The possibility of detecting the indiced-EMF signds a t twice the frequency [A(2wo)]is considered on theoretical grounds. It is shown that the fundamental signal A ( w o ) is proportional to the vibration amplitude A. and to the quantity 6h,/6, in a one-dimensional s stem whereas the doubled signal A(200) is proportional to A. and to d2n,/dZ2.The frequency
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ANALYTICAL CHEMISTRY, VOL. 50, NO. 5, APRIL 1978
doubling method gave a signal/noise ratio better than 300 and reproducibility of better than 0.2% from day to day with a standard sample of nickel. Application of this method to accurate anisotropic measurements is described. Mulay and Marusak (53) have modified a commercially available vibrating sample magnetometer for in-situ investigations on chemical reactions. A low frequency vibrating sample magnetometer has been constructed by Johanssen and Nielsen ( 3 4 ) . A superconducting NbTi magnet is used and the sample is vibrated a t a fixed low frequency of 5 Hz and the amplitude is chosen to give it the greatest content of the first harmonic in the pickup signal. Thus, the magnitude of the signal is made independent of small variations in the vibration amplitude. The relative accuracy of the VSM is 0.17c and no image effects (
Suspensions; Avoiding Lateral Motion of Samples. A Faraday balance suspension made of Nylon monofilament line (1-lb test) is recommended by Villa and Nelson (93)because of its shatterproof nature, diamagnetism, and light weight (density = 1.5 g cm-”). This suspension does not change its length with loads up to 500 mg and a t liquid nitrogen temperature. The advantages of this nylon suspension over quartz fibers are obvious. These authors (93) also describe the use of circular radioactive sources for eliminating the problems arising from static electricity which tend to move the sample bucket (usually made of quartz) close to the surrounding cryogenic chamber (cold finger), which vitiates the weighin s of the sample. These sources are made by evaporating f 7CsCl in 0.5 N HCI to dryness. One source is attached on the outside of the sample chamber about 1 cm higher than the sample position and another source is placed inside a t the bottom of the sample chamber. This arrangement is indeed very satisfactory in our opinion t o circumvent the static electricity problems. However, very strong ferro- (or ferri-) magnetic samples, tend to move toward one of the magnet poles because of a force between such a sample and its “magnetic image” in the pole. Under these conditions, we recommend the use of a sample bucket made of diamagnetic spec-pure copper and a very small amount of the ferro- (ferri-) magnetic material (a few milligrams). This combination reduces the “image-attraction’’ effect and the magnetic force experienced by the sample. T h e true value of the magnetic force on the sample itself is, as always, obtained by subtracting the negative diamagnetic contribution from the bucket. (This procedure is equivalent to adding the numerical value of the buckets contribution to the observed combined force for the bucket plus sample). Spraget and Williams (87) describe a novel balance suspension, which also serves as a thermocouple for use with the Cahn RG electrobalance. T h e setup is used in conjunction with a Faraday susceptibility balance. The thermocouple consists of twisted 0.08-mm enameled wires (0.03% Fe-Au alloy and Cu). The free ends of these wires are connected to the central pivot of the balance and taken along the weighing arm t o the suspension point where it is glued and the suspension allowed t o hang from that point. T h e lower thermocouple junction is kept in contact with the sample. T h e relative susceptibility results for pure tantalum and chromium obtained with this suspension and in fields of 5000 Oe are given. Very good agreement with previous results including a n accurate determination of the spin-flop temperature of Cr
(123.5 f 0.5 K) is given. In our opinion. this type of suspension may be adapted for the Gouy type balance as well. T h e field profile in a superconducting Faraday magnetometer is described by Johannson (33). Lateral stability is obtained both for paramagnetic and ferromagnetic samples. Experimental aspects and the theory of the magnetometer are described. A small ring made of ferromagnetic nickel wire and surrounding the sample tube (6.4 mm in radius) is used which prevents the instability of strongly ferromagnetic (even single crystal) samples, and thus facilitates the centering of the sample a t the desired spot in the field. Other Modifications in Force Type Techniques. A book on weighing designs by Banerjee (3) is indeed useful for understanding the problems in accurate weighings, both from a theoretical and experimental point of view. Hence, it is expected that it would be useful in the design and construction of the Faraday and Gouy type balances. Ray (72) has adapted a Cahn electrobalance model RG for reduction and oxidation studies. His symmetrical design eliminated the disturbing effects such as thermomolecular flow, buoyancy, and gas flow. The electrostatic effect was eliminated with a Pt coating. A sliding double furnace allowed reduction, quenching, and oxidation to be carried out in situ a t elevated temperatures up t o 900 “C. Studies on the reduction and oxidation of Co2-J0 < x < 0.3) are reported. With sufficient ingenuity, we believe that this modification can be adapted for magnetic susceptibility studies with special reference to in-situ type investigations of reactions a t high temperatures. The design and operation of a novel Faraday-magnetometer using superconducting coils is described by Koebler and Deloie (37). The magnetometer uses separate superconducting coils for field and field gradient. The lowest magnetic moment that can be detected is equivalent to magnetic moments produced by 1.06 x 1013 ions with moments of 1 I.LB under conditions of ferromagnetic saturation. The loading capacity of the balance is stated to be 7.53 x loz1 magnetic ions. One ppm of paramagnetic ions incorporated into a diamagnetic matrix can be detected quantitatively within an error of 1%. T h e sensitivity of the magnetometer is high enough t o detect nuclear magnetism. The construction of another field-gradient controlled magnetometer of a Faraday type is described by Nomura and Fujiwara (66). The field gradient applied with an external coil system is described. A sliding mechanism is used to bring the specimen to a position where the field is most homogenous. The hysteresis loop of Ni under a steady field gradient was measured. By supplying the ac currents in phase both to the inhomogenous coil system and the Helmoltz coils, the temperature dependence of the low-field susceptibility was measured. For Ni. a sharp drop in the susceptibility was observed at the Curie point. T h e Curie temperature corresponding to the small quantity of the ordered phase of Ni3h‘In was detected. Matsui and co-workers (42) have developed an automatic magnetic pendulum with a wide range of sensitivity. Their new type of magnetic pendulum can detect forces ranging from to 5 x IO4 dynes exerted on a magnetic specimen 5x placed in a gradient field, and enables measurements to be made on weak magnetic substances (cf., xP = 4.0 X 10’ emu g for a 1.0-g specimen) with an accuracy of 1% and also t e measurement of ferromagnetic moments (cf., I, = 250 Gauss for a 0.1 cm3 specimen) with an accuracy of 0.02%. This feature was attained by balancing not only the moment of forces about the supporting point of the pendulum, but also all the laterally acting forces produced by 2 coils and the specimen. Kazitsyn and co-workers (35)describe a simple and sensitive Faraday magnetic balance, using a permanent-magnet ammeter system with a lever; the force acting on the sample can be compensated for by a current passing through the ammeter coil to a high precision since the current is directly proportional t o the force compensated. Experiments with NaCI, KC1, Bi, etc. showed that this balance works in the susceptibility region 3 x IO-” to m3/kg, with a relative error of 1.2%. Their electrobalance constructed from an ammeter is probably similar to the balances made by the Perkin-Elmer Co. and by the Cahn Co., in the U S A . ; however, their design will aid laboratories which cannot afford the expensive electrobalances. Thermometric Errors in Magnetic Measurements. Kollie and co-workers (38)have analyzed large thermocouple
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thermometry errors caused by magnetic fields. They report that chromel/alumel thermocouples used in a magnetic field indicated temperatures in error by about f150% at 100 "C. Diagnostic tests showed that the errors were caused by the Ettingshausen-Nernst (EN) effect. The EN effect produces a n emf in a conductor, such as a thermocouple, placed in a magnetic field and temperature gradient which are both transverse to the length of the conductor. The heat transfer experiment conducted a t the Oak Ridge National Laboratory in which the temperature measurement errors were encountered is described, and the results of diagnostic tests performed in this experimental apparatus and in auxiliary lab-bench experiments to identify the EN effect are presented. Sources of error, other than the EN effect, for thermocouples used in a magnetic field are discussed. Temperature measurement error due to the effects of time varying magnetic fields on thermocouples with ferromagnetic thermoelements have been described by McDonald (43). Thermocouples with ferromagnetic thermoelements (iron, Alumel, Nisil) are used extensively in industry and in magnetic measurements (with usually the magnetic field turned off). McDonald has observed the generation of voltage spikes within ferromagnetic wires when the wires are placed in an alternating magnetic field. This effect has implications for thermocouple thermometry, where it was first observed. For example, the voltage generated by this phenomenon will contaminate the thermocouple thermal emf, resulting in temperature measurement error. The magnetoresistance effect in "Speer" carbon resistance is reported by Sanches et al. (76). Their findings are important in that many magnetics laboratories employ such resistances for temperature measurements particularly because carbon is "nonmagnetic" (i.e.9 diamagnetic). The authors have calibrated commercially available Speer carbon resistors (100 R,grade 1002) in the range 5-50 mK using a 6oCoConuclear orientation thermometer. Negative longitudinal magnetoresistance effect was observed up to 2.5 T (25 000 Oersteds). Their calibration curves would be indeed useful in making appropriate corrections to temperatures measured in the milliKelvin range ( 5 to 50 mK).
APPLICATIONS Oxygen Analyzers; Magnetic Properties of 02.Several workers, including especially Pauling, devised oxygen analyzers based on its paramagnetic properties [cf. Mulay (47b)l. The O2 molecule exists in ' 2 state and has a temperature dependent paramagnetic susceptibility corresponding to two unpaired electrons. Several commercial analyzers are now available which are based not only on its magnetic property but also on its spectroscopic properties. Recently these have been reviewed by Munday (65). A thermomagnetic gas analyzer for determining large concentrations of oxygen (98-100%) in the presence of nitrogen and argon a t 5 to 50 "C has been developed by Sheinin (77). Thermal convection current is balanced vs. thermomagnetic convection. A thermal conductivity unit is used to balance out temperature changes. The absolute error is 50.1% oxygen when the concentration of O2 is 98-10070 in the standard reference gas. Mulay and Marusak (53)in continuation of Mulay's earlier work (52) have examined the antiferromagnetic coupling between pairs of O2 molecules physically adsorbed on the surface of defect-free y-alumina, whereas the magnetic properties of liquid and solid oxygen have been investigated by Kratsky et al. (39) and by Sakakibara (75). Magnetokinetics Involving Inorganic and Biosystems. A number of workers including Mulay (62) have devised magnetic susceptibility and/or magnetization techniques for following the kinetics of specific reactions and equilibria. Selected examples were surveyed periodically in our earlier reviews, in a monograph by Mulay (47a) and books by Mulay and Boudreaux (48a,b). Oxidation of Pyrite. (Mulay et al. (54) report t h a t the temperature independent paramagnetism of pyrite is of the Van Vleck type and that it does not change with pressure up to -15 kbars.) Mulay et al. (62) point out that the oxidation of pyrite had been studied mostly by standard methods such as TGA and DTA, whereas their new magnetokinetic approach for studying such oxidation processes provides far more information than the older techniques. The kinetics are followed
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using a vibrating sample magnetometer as a probe to quantify the magnetic parameters of the intermediate and final reaction products, as a continuous function of time a t specific temperatures, and as a function of their particle size and superparamagnetic properties. The technological relevance of their work stems partly from the possible magnetic separation of pyrite from coal after its oxidation (or reduction) to ferriand antiferromagnetic compounds. A vibrating sample magnetometer was modified to carry out in-situ reactions isothermally up to 600 "C. Pyrite from Rico, Colo., was crushed and sieved to give particles in the range 250-90 pm. A sample of crushed pyrite (0.100 f 0.001 mesh) was placed in a gold sample tube in which a glass wool bed was inserted. Dry nitrogen was passed at a flow rate of 150 mL/min directly through the sample holder in the furnace until the desired temperature was attained. Nitrogen gas was allowed to flow for an additional 15 min before passing dry air a t the same flow rate. Magnetization was measured as a continuous function of time a t a constant magnetic field of -4000 Oe. The parameters varied were the particle size of pyrite and reaction temperature. Results obtained for temperatures between 4W500 "C, were interpreted in terms of the following reactions: FeS, t FeS, +
0, 0,
--f
a-Fe,O, ' 1 , r-Fe,O,
+ 2S0, + 2S0,
(1) (11)
The formation of the antiferromagnetic o-Fe203and the ferrimagnetic y-Fe2O3was confirmed by Mossbauer spectroscopy. Mulay and Marusak (53)have also developed a technique for following the magnetokinetics of diffusion processes in a pyrrhotite (Fe9Slo),which shows a A-type transition, that is a transition from a (weakly) antiferromagnetic 5C structure to a (very strong) ferrimagnetic 4C structure. Hemoglobin-Monoxide Reactions. A new technique for measuring fast reactions in solution has been demonstrated by Philo (71). The changes in magnetic susceptibility during the recombination reaction of human hemoglobin with carbon monoxide after flash photolysis have been measured with a new high-sensitivity instrument using cryogenic technology. The rate constants determined at 20 "C (pH 7.3) are in excellent agreement with those obtained earlier by photometric techniques. A unique capability of this new method is the determination of the magnetic susceptibilities of short-lived reaction intermediates. The magnetic moment of the intermediate species Hb,(C0)3 was found to be 4.9 f 0.1 p B in 0.1 M phosphate buffer by partial photolysis experiments. This value agrees with the predictions of two-state allosteric models of cooperativity in hemoglobin. Possible applications and improvements to this technique are discussed. Application to Biochemistry. Studies on oxyhemoglobin. It is refreshing to note that the classic magnetic studies by Pauling and Coryell initiated in 1936 on the structure of oxyhemoglobin which was shown to be diamagnetic with the aid of a simple and reliable Gouy balance opened up new avenues to elucidating the structure of several other biosystems, which have been selectively surveyed in our earlier reviews (55-603. Of the several systems studied, surprisingly the structure of oxyhemoglobin itself appears to have become controversial. In a recent article Cerdonio et al. (10)complain that despite spectroscopic (x-ray fluorescence, Mossbauer, and Raman) evidence for the presence of unpaired electrons in the iron-oxygen bond in oxyhemoglobin ( H b 0 2 ) and in carboxyhemoglobin (HbCO),the majority of the papers in the field assume these complexes to be diamagnetic as first proposed by Pauling (cf. 47b). In their paper, Cerdonio et al. report new magnetic susceptibility measurements on frozen aqueous human H b 0 2 solutions which were undertaken to remove this bias and to produce new experimental evidence about the magnetic state of H b 0 2 which is a t variance with the commonly accepted behavior as cited above. Their experimental method, based on their oscillating sample superconducting magnetometer, differs from previous methods mainly in the fact that they scan a wide temperature range, between 25 and 250 K, rather than take measurements only at a single temperature. This procedure allows them to resolve small paramagnetic contributions on top of the dominating background of the frozen protein solution without resorting to less direct subtraction procedures. Their measurements
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showed a temperature-dependent behavior typical of a thermal equilibrium between a ground singlet state and an excited triplet state for two electrons per heme, the energy separation being 1251 = 146 cm-’. By contrast, within the same temperature range, carboxyhemoglobin was found to be diamagnetic, as already reported. In a rebuttal to Cerdonio’s work, Pauling (69) reviewed the published evidence on HbOs and confirmed his earlier (1936) results showing HbOz in blood or in solution at 20 “C to have a zero magnetic moment and pointed out that Cerdonio’s and other workers “paramagnetic” models are unacceptable. He further discusses bond lengths and bond angles for HbOz and HBCO. In related studies, Alpert and Banerjee ( 2 ) report magnetic susceptibility measurements over a wide temperature range (4.5-300 K) on liquid/frozen solutions of deoxygenated human hemoglobin and its isolated chains. Measurements have been done also on human fetal chains, des-Arg and SucNEt-des-Arg hemoglobins. In all the proteins under study, the Fe2+ is in the high spin state ( S = 2). At room temperature, the magnetic moments lie in the range 4.90 (theoretical spin-only value) to 5.45 pB. Local differences between the iron sites are revealed by the low temperature measurements. A mechanism is proposed to explain the effect of phosphate binding on the magnetic susceptibility. Champion et al. (14) have measured the magnetic susceptibility of singly reduced, camphor-complexed cytochrome P-450 from Pseudomonas putida at various temperatures. Computer analysis using a spin Hamiltonian yielded values of D between 15 K and 25 K, which agree with a value of D = 20 K found by low-field variable temperature Mossbauer spectroscopy. This result is compared with the results on deoxyhemoglobin and deoxymyoglobin. Palmer and co-workers (67) have proposed a model for the active center of cytochrome c oxidase (ferrotochrome c:oxygen oxidoreductase, EC 1.9.3.1)in which cytochrome a is a low-spin ferrihemoprotein and cytochrome a3 is a high-spin ferrihemoprotein antiferromagnetically coupled to one of the two Cu2+ions present in the enzyme. It is further proposed that reduction is accompanied by a conformational change in the enzyme, thus exposing the sixth coordination site of cytochrome a3to ligands. With this model it is possible to account for a variety of outstanding results on magnetic susceptibility as well as the results of magnetic circular dichroism, Mossbauer, and EPR spectroscopies. Tucker and co-workers (89) report the preparation and magnetic properties of crystalline complexes of Fe3+ and several aliphatic amino acids. All have a basic molecular constitution [Fe[AA]2HzO]30(C104)7, as determined by optical, magnetic, and Mossbauer measurements. The physical properties of these compounds display a marked similarity to those of ferritin. Aasa and co-workers ( I ) have measured the magnetic susceptibility of the acetazolamide complex of human Co(I1) carbonic anhydrase B between 1.4 and 160 K and have compared their results with E P R measurements. The temperature dependence (2.2 to 50 K) of the magnetic susceptibility of Co(I1) stellacyanin (Rhus uernicifera) is reported by Solomon and co-workers (86). The effective magnetic moment of Co(I1) in the protein is 3.91 f 0.12 1 ~ Nonlinear behavior below 3 K evidences the presence of zero-field splitting attributable to a low-symmetry component of the ligand field. The results are consistent with a structural model based on a distraughted tetrahedral Co(I1) site involving one or more extremely covalent metal-ligand bonds. Moss and Vanngard’s (46) magnetic susceptibility measurements a t low temperatures show accurately that only two of the four copper ions in Lacquer tree Laccase (Rhus uernicifera) are paramagnetic. The nonmagnetic ions, previously suggested to be divalent on the basis of reductive titrations, would then form an exchange-coupled two-copper center possibly similar to that proposed for hemocyanin and mushroom tryosinase. Magnetic Characterization a n d Activity of Catalysts. An important problem especially in heterogeneous catalysis is the characterization of the catalyst (that is, the active catalyst as well as the support and any components formed between these two) at the macro- and microscopic levels and then to establish a correlation between the properties of the catalysts and their activity with respect t o one or more reactions. Magnetic properties provide an appropriate avenue for such studies, especially with regard to transition metal and
metal-oxide type catalysts (including the rare-earth type materials). Mulay and co-workers (49) have shown a way to characterize especially commercial samples such as nickel supported on y alumina which are typically used as methanation catalysts. They have done so by obtaining magnetization (a) vs. field (up to 20 kOe) and temperature (77-600 K) type curves and by electron microscopy. Hysteresis curves yielded coercive force (H,) remainence (ar)and saturation magnetizations (as), following heat treatment of the catalysts between 400-700 “C. These parameters are interpreted in terms of the following properties of constituent particles: (a) supermagnetic, (b) single domain anisotropic, and (c) multidomain. Needlelike “b” and “c” type particles are formed when sample A with 43 wt % of Ni is heated to about 600 and 650 “C, respectively. Another sample B with a higher loading of Ni (67 w t % ) consisted of a larger fraction of “a” type particles which on heat treatment increased H , and a (sat) as expected, but was more thermally resistant to the formation of “c” type particles. Unlike sample A, B did not show a significant decrease in the methanation activity upon the formation of “c” type particles. The methanation reaction: CO t 3H, CH, t H,O +
.
was followed using standard gas chromatographic techniques. The distribution of the superparamagnetic particles in the presence of multidomain particles in various heat-treated samples has been calculated and shown to correlate well with their hydrogen chemisorption activities. Mulay and Yamamura (63) have extended their magnetic characterization studies to other catalysts such as the new Raney-nickel, which is obtained by “spraying” metallic nickel on a substrate of (diamagnetic) stainless steel. Sinhamapatra et al. (84) have investigated the interaction between the active catalyst and support in the nickel-molybdenum-alumina type catalysts by magnetic susceptibility. The effective magnetic moments of the catalysts range from 2.82 to 3.36 p~ which showed the spin-free octahedral Ni(I1). The authors also discuss the ferromagnetic properties of the catalysts. Electronic structure and composition of the surface of a heterogeneous vanadium pentoxidemolybdenum trioxide oxidation catalyst has been studied by Shulga and co-workers (82). The catalyst’s surface was studied by x-ray-electron spectroscopy and magnetic susceptibility and it was shown that, dependin on the concentration of the modifying additive, NaH2P8,, the electronic state of the V and the ratio of the V and Mo concentrations on the surface change. The results were correlated with the activity of the catalyst. Reference should be also made to recent articles in the Journal of Catalysis and in the Journal of Surface Science concerning magnetic characterization of several other catalysts. Characterization of Carbon Fibers. In a recent chapter (48a) and in an earlier review (59), we showed that temperature dependent studies by Mulay et al. (48a) on the diamagnetism of various carbons and graphites provided an elegant method for their structural characterization. T o our list, we add an important contribution by Scott and Fischbach (79) who studied the diamagnetic anisotropy of carbon fibers obtained by the pyrolysis of rayon, cellulose, and polyacrylonitrile (PNA). The interest in the synthesis of such carbon fibers stems from the fact that these do provide mechanically strong materials, Le., materials with high tensile modules (E). These fibers are often used as a component which when embedded into other suitable matrix materials gives a composite of even greater mechanical strength. Scott and Fischbach showed that magnetic susceptibility measurements (carried out with the Faraday balance) on small bundles of the aligned carbon fibers are indeed very useful in the characterization of carbon fibers as summarized below. The total susceptibility xi of the carbon fibers varied systematically with the tensile modules E. The behavior typical of fibers from rayon or isotropic pitch differed significantly from that of fibers from polyacrylonitrile, because of differences in precursor chemistry and processing procedures. On the other hand, the anisotropy ratio (radial over axial susceptibility) was found to be approximately a linear function of E for all fiber types, regardless of whether the layer-plane preferred orientation texture is developed spontaneously with heat treatment or is induced by hot stretching. Quantitative agreement with x-ray diffraction
ANALYTICAL CHEMISTRY, VOL. 50, NO.
determinations of the texture resulted from the assumption t h a t the fiber principal susceptibility x ' ~has the crystalline graphite value and only x l C is strongly structure dependent. T h e magnetic behavior of fibers was shown to be similar to that of glassy carbons, consistent with a common ribbon-layer morphology. This, together with the influence of strong orientation texture on xT of the fibers, suggested that the ribbon straight-segment length may play an important role in determining the magnitude of the diamagnetism. Decomposition of Austenite. The decomposition of austenite (Fe,C) using a specially designed VSM for high temperature studies is reported by Shapavalov and co-workers (816). In the magnetometer developed for use at measurement temperatures >lo00 "C, cylindrical C steel standards 1-6 mm in diameter were used, characterized by a rather low strength, but a long transformation time of the overcooled austenite. T h e sensitivity of the magnetometer determined by means of powdered standards with a known Fe content is 0.5% of the ferromagnetic phase; this refers to an arbitrary stage of austenite decomposition. The device permits a direct reading of the results and is fitted with a recording system. The results are presented for the determination of C steel austenite during isothermal decomposition. The device may also be used for studying austenite decomposition during continuous cooling in air. Valenzuela and Miller (91) describe a simplified apparatus for detecting solid state transformations by an ac induction technique a t elevated temperatures. In this simple but sensitive apparatus, detection is based on the changes in magnetic permeability (susceptibility) and/or electrical resistivity accompanying the solid state reaction. The apparatus is constructed from easily available components such as the laminated iron core of a small high frequency inductor, an audio oscillator (loo0Hz), etc. Constructional details are given and examples of solid-state transformation are given, which involve the precipitation of a nonmagnetic ferrite (ct) from the austenite (7) region. Determination of Spin Concentrations. In our earlier reviews (55-61) and in a monograph (47a), it was shown that magnetic susceptibility as well as EPR spectroscopy provide elegant probes for determining the concentration of spins (magnetic ions, free radicals, etc.) in many systems. Servant ( 8 1 ~has ) brought to our attention that "Magneto Microwave Effects" (such as the Microwave Faraday Effect, VoightCotton-Moutton Effect, etc.) present several advantages over the E P R technique and the absolute determination of spin concentrations. Since this topic is beyond the scope of our review, we give a few selected references to Servant's contributions ( 8 1 ~ ) . Mixed Valence and Fluctuating Valence Systems. As explained under the section on "Chapters, Reviews and Books", magnetic susceptibility studies are now being used to understand a number of basic and technologically significant properties of "mixed valence" and "fluctuating valence systems". In the first category we have periodically reviewed (56-60) the work of Mulay and co-workers on the Ti,On,-l type oxides. Mulay et al. (50) have correlated the spin-concentration measurements on Ti305 (which contains both the paramagnetic Ti3+ (3d') and the diamagnetic Ti4+(3d0) ions) with the available electrical conductivity measurements to identify the site of the paramagnetic center contributing to the observed magnetic properties (i.e, susceptibility and E P R spectra). It should be pointed out that the extensive magnetic work by Mulay and co-workers on the oxides of titanium has led them to investigate the use of the Ti-0 electrodes for the photocatalysis of water using solar energy (51). In the second category, SmS provides an interesting example, in that this sulfide at normal atmospheric pressure and room temperature is black but on application of pressure (-6 kbars) it changes to a golden yellow color. This has been explained on the basis of a fluctuating valence intermediate between Sm2+and Sm3+with an absence of magnetic ordering even a t low temperatures. Mulay and Corder0 (cf. 31) report measurements of magnetic susceptibility (x)for SmS alloyed with GdS, LaS, and YS as a function of pressure ( P ) and of composition ( x ) of the dopant a t 295 K. A sharp decrease in x similar to t h a t of SmS when going into the Intermediate Valence (I.V.) state is obtained. x of Sm,RsGdo15Swhich retains the high pressure phme metastably has been measured
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at 1 atm for several temperatures below ambient. x deviates from the simple additivity law for SmS and dopant when ( x ) is varied. This has been attributed to several mechanisms, among which conduction electron enhancement of Sm-Sm exchange interaction and an increase in valence due to alloying are the most important. A gradual increase in the valence of Sm with pressure is also observed. I t is concluded that the moment of the Gd ion has no role in the transition to the I.V. state resulting from either pressure or alloying and that these two parameters are not equivalent for these alloys.
ACKNOWLEDGMENT We are grateful to Diane Muchler and Maria Rossi for their expert and above all cheerful assistance in the preparation of this review. One of us (L.N.M.) sincerely thanks Drs. Candela and Mundy of the National Bureau of Standards for giving a thorough demonstration of their SQUID magnetometer and thanks Dr. R. T. Lewis of the Chevron Research Lab for informative correspondence concerning the measurement of specific (per gram) susceptibility with SQUIDS. LITERATURE CITED (1) Aasa, R., Hanson, M., and Lindskog, S., Eiocbem. Eiophys. Acta, 453, 211 (1976). (2) Alpert, Y., and Banerjee, R., Eiocbem. Eiopbys. Acta, 405, 144 (1975). (3) Banerjee, K. S., "Weighing Designs", Dekker, New York, N.Y., 1975. (4) Beckley, P., and Drake, A. E., J , Pbys. E , I O , 443 (1977). (5) Birss, R. R., Keeler, G. J., and Shepherd, C. H., J . Pbys. E , 9, 963 (1976). (6) Birss, R. R., Keeler, G. J., and Pomfret, D., J . Pbys. E , 9, 635 (1976). (7) Bragg, E. E., and Seehra, M. S., J . Pys. E , 9, 216 (1976). (8) Candeia. G, A., and Mundy, R. E., National Bureau of Standards. Gaithersburg, Md., personal communication. (9) Cerdonio, M., Cosmelli, C., Romani, G. L., Messana, C., and Gramaccioni, C., Rev. Sci. Instrum., 47, 1 (1976). (10) Cerdonlo, M., Congiu-Castellano, A,, Mogno, F., Pispisa, B., Romani, G. L., and Vitale, S., Proc. Natl. Acad. Sci. USA, 73, 398 (1977). (11) Cerdonio, M., Messana, C., I€€€ Trans. Magn., mag 11, 728 (1975). (12) Cerdonio, M., Messana, C., and Gramaccioni, C., Rev. Sci. Instrum., 47, 1 6 6 1 l\ iI a " .7vm ,. (13) Cerdonio, M., Mogno, F., Romani, G. L., Messana, C..and Gramaccioni C., Rev. Sci. Instrum.. 48, 301 (1977). (14) Champion, P. M., Miinck, E., Debrunner, P. G., Moss, T. H., Lipscomb, J. D.. and Gunsalus. I. C.. Eiocbem. Bioobvs. Acta. 376. 579 11975). (15) Chen, Chih-Wen, "Magnetism and Metallurgy of Soft Magnetic Materials';, North Holland Co., Amsterdam-New York, 1977. (16) Chiswell B., and Grigg, E. C. M., "S. I . Units", Wiley and Sons, Australia R y . Ltd., Sydney-NewYork, 1971. (17) Clarke. J., AIP Conf. Proc., 29, 17 (1976) 1181 Coilinson. D W . and Molvneux. L. "Methods in Palaeomaanetism". D. W. Collinson, K. M. Kreer, and's. V. kuncorn, Ed., Elsevier, Amsterdam, 1967, pp 368-7 1. (19) Dirac, P. A. M.. "Spinors in Hilbert Space", Plenum Press, New York, N.Y., 1974. (20) Erdmann, J. C., Tech. Met. Res., 7, Part 1, R. F. Bunshah, Ed., Wiley, New York, N.Y., 1972. (21) Foner, S., Rev. Sci. Instrum., 47, 520 (1976). (22) Foner. S.,"Magnetism: Selected Topics", Gordon, New York, N.Y., 1976. (23) Gallop. J. C., and Petley, B. W., J . Pbys. E , 9, 417 (1976). (24) Gates, J. V.. 11, and Potter, W. H., Rev. Sci. Instrum., 47, 115 (1976). (25) Geddes, L. A., and Baker, L. E. "Principles of Applied Biomedical Instrumentation", Wiley, New York, N.Y., 1975. (26) Glick, M. D., and Lintvedt, R. L., "Structural Magnetic Studies Transition Metal 3 Poly Ketonates", "Progress in Inorganic Chemistry", Vol. 21, S.J. Lippard, Ed., Wiley-Interscience, New York, N.Y., 1976, pp 233-260. (27) Grodski, J. J., and Dixon, A. E., Rev. Sci. Instrum., 47, 938 (1976). (28) Guy, C. N., (a) J . Pbys. E , 9, 790 (1976). (b) Ibid., 9. 433 (1976); See also Ph.D. thesis, Cambridge University, 1974. (29) Hauser, J. J., and Antosh, C. M., Rev. Sci. Instrum., 47, 156 (1976). (30) Howard, D. W., and Wallace G., J , Pbys. E , 9, 257 (1976). (31) Huang, S., and Chu, C. W., Ed., "High Pressures and Low Temperatures", R O C . of a Conference held on this topic in Cleveland, Ohio, July 1977, Plenum Press, New York, N.Y., 1978, in press. (32) Jackson, J. D., "Classical Electrodynamics", Wiley, New York, N.Y., 1962. (33) Johannson, T. J . Pbys. E , 9, 164 (1976). (34) Johanssen, T., Nielsen, K. G., J . Pbys. E , 9, 852 (1976). (35) Kazitsyn, N. V., Lysak, A. T., Shershakov, P. N., Shuruwv, P. A., and Yurkov, V. A., h e r . Tech., 3, 72 (1975) (Russ). (36) Ketchen, M. B., Goubau, W. M., Clarke, J., and Donaldson, G. B., I€€€ Trans. Maon.. maa-13 (1). 372 (1977). (37) Koebler, 6, Del06 F., %r, Keriforschungsanbge Juleich, 91, 1305 (1976): Cbem. Abstr.. 85, 1 8 5 8 9 7 ~(1976). (38) Kollie, T. G., Anderson, R. L., Horton, J. L.. Roberts, M. J., Rev. Sci. Instrum., 48. 501 (1977). (39) Kratski, K. W., Acta phvs. Acad. Sci. Hum., 39, 15 (1975): Chem. Abstr.. 84, 1296282 (1975) (40) Levy, R A , and Hasegawa, R "Amorphous Magnetism41 , Plenum Press New York N Y 1977 (41) Lewis, R T , Rev So Instrum , 47, 519 (1976) (42) Matsui, M , Nishio, H , and Chtkazumi, S , Jpn J Appl Phys , 15, 299 (1976) (43) McDonald, D W , Rev SCI Instrum , 48, 1106 (1977) . - - I
~I
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5, APRIL 1978
(44) Miclea, C., Nicolea, I., Stud. Cercet. Fiz., 70, 1061 (1975): Chem. Abstr., 84, 25141u (1976). (45) Mallinson, J., J . Appl. Phys., 37, 2514 (1966). (46) Moss, T. H., and Vanngard, T., Biochem. Biophys. Acta, 31, 39 (1974). (47) (a) Muby, L. N., Anal. Chem., 34, 343R (1962). (b) Mulay. L. N., "Magnetic Susceptibility" (A reprint monograph),Krieger Publishing Go (Wiley), Huntington, N.Y., 1966. (48) (a) Mulay, L. N., and Boudreaux, E. A,, Ed., "Theory and Applications of Molecuhr Diamagnetism", (b) Boudreaux, E. A,, and Muiay, L. N., Ed., "Theory and Applications of Molecubr Paramagnetism", Wiley-Interscience,New York, N.Y., 1976. (49) Mulay, L. N., Everson, R. C., Mahajan, 0. P., and Walker, P. L., Jr., in "Amorphous Magnetism-11", R. Hasegawa and R. A. Levy, Ed.. Plenum Press, New York, N.Y., 1977. (50) Mulay, L. N., Houlihan, J. F., and Madacsi, D. P., Mat. Res. Bull., 11, 307 (1976). (51) Mulav, L. N., Houlihan. J. F.. Madacsi. D. P.. and Walsh. E. J.. Mat. Res. Bull, 11, 1191 (1976) (52) Mulay, L N , and Keys, L K , J A m Chem SOC, 86, 4489 (1964), 87, 1192 (19651 > ---, (53) Mulay, L. N., and Marusak, L. A,, to be published. (54) Mulay, L. N., and Marusak, L. A . , Mat. Res. Bull., 12, 1009 (1979). (55) Mulay. L. N.. and Mulay, I.L., Anal. Chem., 36, 404R (1964). (56) Mulay, L. N., and Mulay, I . L., Anal. Chem., 38, 501R (1966). (57) Mulay, L. N., and Mulay, I. L., Anal. Chem., 40, 440R (1968). (58) Mulay, L. N., and Mulay, I.L., Anal. Chem., 42, 32% (1970). (59) Mulay, L. N., and Mulay, I.L., Anal. Chem., 44, 324R (1972). (60) Mulay, L. N., and Mulay, I . L., Anal. Chem., 46, 490R (1974). (61) Mulay. L. N., and Mulay, I.L., Anal. Chem., 48, 314R (1976). (62) Muhy, L. N., Walker, P. L., Jr., and Marusak, L. A., I€€€ Trans, Mgnefics, mag-12, 890 (1976). (63) Mulay. L. N., and Yamamura, H., to be published. (64) Mullins, C. E., J . Soil Sci., 28, 223 (1977). (65) Munday, C. W., VDIBer., 199, 25 (1974); Cbem. Abstr., 84, 12551a (1975). (66) Nomura, M., and Fuiiwara. H.. J . Sci. Hiroshima Univ.. Ser. A : Phvs. Chem , 40 (2), 219 (1976) (67) Palmer, G I Babcock, T I and Vckery, L E , R o c Natl Acad S o U S A , 73 2206 (19761 (68) -Pa%s, D.,~Ed.,"Valence Instabilities and Narrow Band Phenomena", Plenum Press, New York, N.Y., 1976. (69) Pauling, L., Proc. Nat. Acad. Scl. U.S.A., 74, 2612 (1977). (70) Pekolski, A., "Magnetism in Metals and Metallic Compounds", Plenum Press, New York, N.Y., 1975. (71) Philo, J. S., Proc. Nat. Acad. Sci. U . S . A . , 74, 2620 (1977). (72) Ray, S. P., Rev. Sci. Instrum., 48, 693 (1977).
d.
(73) Reeves, R., J . Phys. E . 5 , 547 (1972). This paper gives a good analysis of the alternating force magnetometer and the V.S.M. (74) Rose-Innes, A. C.. J . Phys. E , 10, 1142 (1977). (75) Sakakibara, A,, Mem. Sch. Eng. Okayama Univ.. 10, 81 (1976). (76) Sanchez, J.. Benoit, A., and Flouquet, J., Rev. Sci. Instrum., 48, 1091 (1977). (77) Sheinin, D. M., Prib. Sist. Upr., 11. 31 (1976) (Russ): Chem. Abstr.. 86. 197R47m (1977) ~
(78) Schneider, E. E., J . Phys. E , 10, 2 (1977). (79) Scott, C. B., and Fischbach, D. E., J . Appi. Phys., 47, 5329 (1976). 180) Sena. F. J.. Order No. 75-18. 897 (19751. Xerox Univ. Microfilms. Ann Arbor, Mich. 'See Diss. Abstr.'lnt. 6 , s e , ' i 2 i i (1975). (81) (a) Servant, Y., Physica, 89B, 280 (1977); J . Magn. Res., 24, 235 (1976). (b) Shapavalov, S. I . , Senko, V. F., and Alimov. V. I., Zavod. Lab.. 42 (3). 297 (1976); Chem. Abstr., 85, 115676X (1976). (82) Shulga, Yu. M., Ivleva. I.N., Shinmanskaya, M. V., Margolis, L. Ya., and Borod'Ko, Yu. G., Zh. Fiz. Khim., 49, 2976 (1975); C k m . Abstr., 84, 65657y (1975). (83) Simpson, A. W., Wiss. Z. Tech. Univ. Dresden. 23, 1029 (1974). (84) Sinhamahapatra, P. K., Sharma, L. D., and Sharma, D. K., Z. Phys. Chem. (Leipzig), 258, 41 (1977). (85) Smart, J. S.,"Effective Field Theories of Magnetism", Saunders, Fhihdelphia, Pa., 1966, p 6. (86) Solomon, E. I . , Wang, R. H.. McMillin, D. R., and Gray, H. B., Biochem. Biophys. Res. Commun., 69, 1039 (1976). (67) Spraget, H. W, G., and Williams, D. E. G., J . Phys. E , 9 , 317 (1976). (88) Taylor, R. H., "Magnetic Ions in Metals", Halsted Press, New York, N.Y., 1977. (89) Tucker, W. F., Asplund, R. O., and Holt, S L., Arch. Biochem. Biophys., 116, 433 (1975). (90) Van Vleck, J. H., "Theory of Electric and Magnetic Susceptibility", Oxford Univ. Press, London, 1932. (91) Valenzuela, J., and Miller, A. E., Rev. Sci. Instrum., 48, 191 (1977). (92) Verge, C.. Altounian, A., and Datars, W. R., J . Phys. E , 10, 16 (1977). (93) Villa, J. F., and Nelson, H. C., J , Chem. Educ., 53, 28 (1976). (94) Vonsovskii, S.,"Magnetism", Vois. I & 11, Wiley, New York, N.Y., 1974. (95) Webb, A. W., Gubser, D. U.. and Towle, L. C., Rev. Sci. Instrum., 47, 59 (1976). (96) Weber, H. W., "Anisotropy Effects in Superconductors", Plenum Press, New York, N.Y.. 1977. (97) Weiss, A., and Witte, H., "Magnetochemistry: Principles and Applications", Verlag-Chemie, Weinheim, Germany. (98) Weissbiuth, M., "Hemoglobin", Springer Verlag, New York-Heidelberg, W. Germany, 1974. (99) Zaveta, K., Wiss. 2. Tech. Univ., Dresden, 23, 1035 (1974).
Infrared Spectrometry Robert S. McDonald General Electric Corporate Research and Development Center, Schenectady, N. Y. 1230 I
INTRODUCTION This review covers publications cited in Chemical Abstracts (CA), volumes 84-87 (1976-77), through the December 26, 1977 issue. Selection of References. The initial selection was based on a computer search of Chemical Abstracts Condensates (CAC) on magnetic tape. As in previous years, the bibliography was managed throughout in computer readable form by means of an experimental computer program called LISE (Literature Search and Edit), which was described briefly in the reviews for 1970-71 and 1972-73. This review has continued to serve as a vehicle for the development of LISE as a n automated bibliographic tool. This year, as in 1976, the bibliography is being submitted to Analytical Chemistry in computer readable form on magnetic tape which was generated via LISE from the CAC database. Thus, aside from selection of references, formatting, capitalization of titles, and minor corrections, the bibliography was effectively keyed by CA. T h e general procedure was similar t o that used previously and described in the review of 1974-75. 0003-2700/78/0350-282R$05.00/0
The full CAC database for 1976-77 contains about 801,000 citations. The total number of citations pertinent to infrared spectrometry is about 8200, approximately 1% of the items covered by CA. Obviously, many arbitrary choices have been required to trim the number of citations to the approximately 800 which make up the bibliography. Books and reviews have been selected to give broad coverage, not only of infrared analysis, but also of other topics which provide support for infrared analytical work. The remaining papers have been selected with two points in mind, (l), to cover areas in which new developments are underway, and (2), to give broad coverage of applications of infrared in chemical analysis. Regrettably, it has been n e c e s s q to exclude journal articles which describe applications of infrared spectrometry to structural problems of small molecules, to the study of unstable species, adsorption and catalysis, and other topics which lie more in the field of physical chemistry than analytical. Patents have also been excluded. The bibliography is mainly limited to work which has been cited in CA. Generally, the cut-off for inclusion of journal articles is late summer or early fall of 1977. Organization of the Bibliography. The bibliography is divided into thirteen sections with separate numbering for 1978 American Chemical Societv
