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HIS reviev.. covers papers published since the preparation of the last review in this series (28). I n a few cases earlier papers, not previously reviewed, are cited. Those papers are not included which present Raman spectra solely for theoretical molecular determination by means of frequency assignments to normal vibrations. The period covered is notable mainly for developments in instrumentation.
Sheppard (16). Rosenbaum, Cerato, and Lauer ( 2 4 ) suggest the use of a tungsten lamp standardized as Illuminant A by the S a tional Bureau of Standards to correct an observed spectrum for the wave-length dependence of photomultiplier tube sensitivity and transmission of the spectrometer. Shorygin, Kuzina, and Osityanskaya (26) discuss the effects of changes in molecular structure on the intensities of characteristic lines.
APPARATUS
ANALYTICAL APPLICATIONS
White, Alpert, and DeBell (31) describe a grating photoelectric spectrometer and auxiliary apparatus such as an image slicer, multiple traversal Raman tube, and internally water-cooled spiral mercury arc. The Perkin-Elmer Corp. ( 1 7 ) has announced the commercial availability of a grating instrument based on a standard monochromator. Another interesting instrument was placed on the market by the Applied Physics Corp. (8). This makes use of a double grating monochromator to minimize the undesirable effects of stray radiation and Tyndall scattering from the sample. To achieve maximum utilization of light the monochromator has two entrance slits, an ingenious image slicer is used, and the detecting system includes a rotating sector mirror and two photomultiplier tubes which receive light alternately. Excellent spectra are obtained with a sample volume of 0.1 ml. and a scanning speed of 10 cm.-’ per second. Skinner ($7) discusses the interrelationship of slit width and scanning speed. Brandmuller (6) studies the illumination of a spectrograph by light from a Raman tube. He points out some advantages in not using a condenser lens between the tube and the spectrograph slit. Brandmuller and ?.loser ( 7 ) give details for the conversion of a Steinheil spectrograph to a recording spectrometer. Welsh and coworkers (SO) describe the apparatus they use in their outstanding work on the Raman spectra of gasea. A high-current, water-cooled mercury arc lamp is reported by Shull (86).
Robert (22) describes the application of Raman spectra ohtained with a recording spectrometer converted from a spectrograph to the analysis of petroleum products such as gasoline cute, aromatic concentrates, and “white” oils (using Hg 5461-4 excitation). He also presents data for acetone and isopropyl alcohol mixtures in aqueous solution. Xylene isomers are determined by Takei (89). The products of low molecular weight in the aluminum chloride-catalyzed polymerization of ethylene to lubricating oils are analyzed by Geiseler, Kaufhold, and Runge (10). The effect of a variety of substituents on the ring frequencies of substituted cyclohexanes has been studied by Chiuroglu, Doehaerd, and Maquestiau (9). Piaux and Gaudemar (19) have determined the purity of allenic hydrocarbons obtained 1)the propargylic rearrangement. Variations in the frequency shift of the carboxyl line in branched aliphatic ketones are reported by Heilmann and ilrnaud ( 1 2 ) and similar considerations for C = C and C = 0 lines are presented by Kirrmann, Federlin, and Bieber (14). Batuev and Antsus ( 2 ) identify an oxidation product of diisobutylene. Artamonov (1 i has investigated the acids formed in the hydrogenation of regetable oils. The three-component mixture of mono-, di-, and trichloroacetic acids in the molten state has been analyzed by del Pilar Jorge and Barcelo PIlatutano ( I S ) . Goubeau and colvorbers: (11) use the combination of Raman and infrared spectroscopy to identify the trimer of hydrocyanic acid as 1,3,5-triazine. The products of the reactions between sulfuric acid and phenol and sulfuric acid and cresol are determined by Pershina and Raskin
INTENSITIES
(18).
There is considerable activity in the study of the theoretical and experimental factors which determine the observed intensities of Raman lines. This work offers the interesting possibility that Raman line intensity relative to some standard line (such as the 459 em.-’ line of carbon tetrachloride) may be obtained independent of the apparatus used. If this can be done, then calibrations for quantitative analysis obtained with one apparatus may be transferred to another apparatus without significant loss of accuracy. Bernstein and Allen (6) have carried out a careful study of the problem of expressing the integrated intensities of Raman lines in terms of a standard intensity scale. They include all corrections which appear to be relevant. Luther and Lohrengel (16) express Raman line intensity in terms of a molar scattering coefficient. On the basis of an examination of a number of analytically useful lines of normal paraffins, they conclude that the molar scattering for C-H frequencies can be calculated from group increments. An experimental study of the intensities of the lines of CC14, CHCls, and CHzClz is reported by Marrinan and
Baudler has investigated the spectra of esters of phosphoric and phosphorus acids ( 4 ) and aqueous solutions of hypophosphorus acid (S). He presents characteristic frequencies for a number of bonds. The complex cadmium and mercuric halide anions in aqueous solutions have been studied by Rolfe, Sheppard, and Koodward (23). Woodward and Bill ( 3 2 ) use the intensities of lines attributed to InBr4- to follow the extraction of indium bromide by ethyl ether and methyl isobutyl ketone from aqueouc solutions containing hydrobromic acid. The structures and stabilities of complexes between diborane and methyl ether, ethj 1 ether, or tetrahydrofuran are discussed by Rice and Uchida (21). Shifts in the position of the C = 0 line in salicylaldehyde are used by Puranik ( 2 0 ) to study the transition from intramolecular hydrogen bonding to intermolecular hydrogen bonding. LITER4TURE CITED (1) drtainonov, P. A, Zhur. Priklad. Khim. 28, 775 (1955). (2) Batuev, 11.I.,.Intsus, L. J., Doklady Akad. -\’auk S.S.S.R. 100, 267 (1955).
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Baudler, M., Z . a m r g . u. allgem. Chem. 279, 115 (1955). Baudler, M., Z . EEektrochem. 59, 173 (1955). Bernstein, H. J., Allen, G., J . Opt. Soc. Anier. 45, 237 (19551. Brandmuller, J., Optik 12, 389 (1955). Brandmuller, J., Moser, H., Ann. Physik 13, 253 (1953). Chem. Eng. .Vews 33, 4232 (1955).
Chiuroglu, G., Doehaerd. T., Naquestiau, h.,BUZZ.soe. ehim. Belges 63, 470 (1954).
Geiseler, G., Kaufhold, R., Runge, F., Erdol
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Kohle 7 , 281
(1954).
Goubeau, J., Jahn, E. L., Kreutrberger, d.,Grundniann C., J . Phys. Chem. 58, 1078 (1954).
Heilmann, R., Arnaud, P., Bull. soc. chim. France 1954, 1257. Jorge, M.del P., Matutano, J. R. B., Anales real soc. espafi.f i s . u qubm. (Madrid) 51B, 125 (1955). Kirrmann, ii., Federlin, P., Bieber, P., BUZZ.so?. chini. Fmnce 1954, 1466.
Luther, H., Lohrengel, E., Brennstof-Chem. 35, 338 (1951). >laminan, H. J., Sheppard, S . , J . O p t . SOC.Atner. 44, 815 (1954). Perkin-Elmer Instrument .Yews 5 , S o . 4 , 6 (1954).
REVIEW OF FUNDAMENTAL DEVELOPMENTS
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(18) Pershina, E. V.,Kaskin, S.S., DoiZady Akad. Nauk S . S . S. B . 100, 123 (1955). (19) Piaux, L., Gaudemar, Jl., Compt. rend. 240, 2328 (1U.5). (20) Puranik. P. G., J . Chem. Phys. 23, 761 (1955). (21) Rice, B., Uchida, H. S., J . Phys. Chem. 59, 650 (1958). (22) Robert, L., Spectrochim. Acta 6 , 115 (1953). (23) Rolfe, J. A . , Sheppard, D. E., Woodward, L. A., Trans. Faracday Soc. 50, 1275 (1954). (24) Rosenbaum. E. J.. Cerato. C. C . . Lauer. J. L.. J.Oat. SOL A m . 42, 670 (1952). ( 2 5 ) Shorygin, P. P., Kurina, L., Osityanskaya, L., M&&im. Aha 1955, 630. (26) Shull, E. R., J . Opt. SOC.Amer. 45, 670 (1955). (27) Skinner, J., Spectrochim. Acta 6, 110 (1953). (28) Stamm, R. F.. A s a ~C. m x . 26, 49 (1954). (29) Takei, T., J . Chem. SOC.Japan. Pure Chem. Sect. 74, 965 (1953). (30) Welsh. H. L., Stansbury, E. J., Romanko, J., Feldrnbn, T., J . Opt. Soc. Amer. 45, 338 (1955). (31) White, J. L7.< dlpert, N. L., DeBell, -4. G., Ibid., 45, 154 (1955). (32) Woodward, L. A . , Bill, P. T., J . Chern. SOC.1955, 1699.
M A X SWERDLOW, National Bureau o f Standards, Washington, D. C. A. 1. DALTON, National Institutes o f Health, Bethesda, Md. L. S. BIRKS, Naval Research Laboratory,Washington, D. C.
RENDS reported in the previous review (256) have continued to develop in a manner that has given electron microscop)- a responsible role in delineating the relationship of the microstructure of solids with their properties and behavior. This method in conjunction with other methods of analysis has not only established itself as a necessary line of research in chemistry, physics, and biology but is becoming a valuable aid in industry, :tgIiculture, and medicine. 1:ngineering developments in the transmission magnetic-type electron microscope have, in the past decade, made the instrument into a reliable laboratory tool. With most major countries inanufacturing a t least one electron microscope, recent advances iri electron optics should continue to be incorporated in the newer ( oniniercial designs. Nost current models are capable of a resolution of 20 A. (Radio Corp. of America, Camden, N.J., Type FXU-3B; Xorth Bmerican Phillips Co., Inc., Mt. Vernon, S.T.,Type EM-100A); one is capable of 6 A. (Siemens Br Halske .iktiengesellschaft, Werneraerk fur Messtechnik, Karlsruhe, Germany, Elmiskop I ) . Present knowledge about the inter:i( tion of electrons with matter indicates that a practical limit t o the resolving power of the electron microscope is about 5 A. Although this figure is two orders of magnitude worse than the theoretical limit imposed by the wave nature of electron beams, there is hope that the electron microscope may yet make visible the ultimate goal-the structure of the atomic lattice. Considerable effort still centers around problems related to optimum performance of the instrument. Approximately 1000 elertron niicroscopes are in use today. hIost are far from faultflee. Consistent high quality results are still matters for the well tiained specialist. The technical excellence of most of the electIon micrographs in evidence attests to their painstaking skill. Although high-resolution electron microscop)- is required for the elucidation of macromolecules, much of the experimentation is concerned with structural details just beyond the resolution of the light microscope. There has been a steady shift of emphasis
from problems related to instrumentation to problems related to specimen preparation. Mastery of these elements in electron microscopy is only prerequisite, however, to the more discriminating aspect of the problem-namely, the valid interpretation of the observed microstructure with regard to concepts concerning processes of growth, degradation, and function. The information and confidence gained from properly planned and controlled experiments combining the electron microscopical approach with other independent methods of analysis have resulted not only in confirming many present ideas but in revising and filling in gaps in existing knowledge.
MEETINGS AND SOCIETIES The scope and quality of meetings held by an increasing number of societies devoted to the science of electron microscopy provide good indications of recent developments. Annual conventions of national organizations were held in England, Germany, Japan, and the United States. Local regional meetings within the various countries are held with regularity to satisfy the wide interest in electron microscopy. The Annual Conference of the Electron Microscopy Group of the Institute of Physics was held a t Birkbeck College, University of London, on Xov. 10 and 11, 1953. As with previoue conferences of the British group, papers were read concerning the electron microscope and a wide range of its applications. Twenty-three papers were given reporting on electron optics, chemical applications, reflection microscopy, carbon, silica, and plastic replica techniques, thin sectioning, and particulate structures in biological materials. The proceedings were summarized by Challice (38). This same group held its 1955 conference on July 5 to 7 at the University of Glasgow. Forty-one papers were read: 16 on instrumentation and general techniques, four on crystals, plastics, and air pollution studies, and six on metallurgical applications.
