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J. R. Brandon and R. F. Firestone
with the maximum a t less than 185 nm is red-shifted by the vinyl substituent in VOC to 194 nm. The interaction is reduced by the insulating methylene group in AOC and therefore its maximum is near 185 nm. The methyl group in isopropenyl-o-carborane increases the red-shift caused by vinyl owing to hyperconjugation. The absorption maximum for o-carborane can be estimated to be about 160 nm from the calculations of Potenza and L i p ~ c o m b The .~ large 1.4 eV red-shift caused by vinyl mupt involve both induction and resonance. Alternatively, the weak absorption of ethylene at 200 nm is known to be both shifted and enhanced by substituents10 and the absorption maximum at 194 nm for VOC could be assigned to such an absorption blue-shifted by the acidic, electron-withdrawing ocarborane cage. With this assignment, however, the absorption peak for AOC is expected to be at longer wavelengths than VOC because the methylene group partially shields the double bond from the o-carborane cage. The peak for AOC near 185 nm suggests that this alternative explanation is not correct. Acknowledgment. The authors wish to thank the U. S. Atomic Energy Commission which supported this work under Research Contract AT-(40-1)-3781.
References and Notes (1) T. J. Klingen and J. R. Wright, J. Inorg. Nucl. Chem., 35, 1451 (1973), and references cited therein. R. M. Thibault and T. J. Klingen, unpublished results. K. M. Bansal and R. H. Schuler, J. Phys. Chem., 74,3924 (1970). J. A. Potenza and W. N. Lipscomb, Inorg. Chem., 5, 1471 (1966). R. N. Grimes, "Carboranes," Academic Press, New York, N. Y., 1970, pp 54-1 50. (6) R. M. Thibault and T. J. Klingen, J. Inorg. Nucl. Chem., in press. ( 7 ) T. J. Klingen and J. H. Kindsvater, MOL Cryst., Liquidcryst., in press. (8) J. R. Wright and T.'J. Klingen, J:lnorg Nucl. Chem., 32, 2853. (1970). (9) W. A. Cramer in "Aspects of Hydrocarbon Radiolysis," T. Gaumann and J. Hoigne, Ed.. Academic Press, London, 1968, Chapter 4. (10) K.-D. Asmus, J. M. Warman, and R. H. Schuler, J. Phys. Chem., 74, 246 (1970). (11) J. M. Warman, K.-D. Asmus, and R. H. Schuler, Advan. Chem. Ser., No. 82, 25 (1968). (12) R. A. Holroyd, J. Phys. Chem., 70, 1341 (1966). (13) J. L. McCrumb and R. H. Schuler, J. Phys. Chem., 71, 1953 11967). (14) k. A. Holroyd and G. W. Klein, J. Phys. Chem., 69,194 (1965). (15) J. C. Bevington, "Radical Polymerization," Academic Press, New York, N. Y., 1961, p 114. (16) (a) F, Hirayama and S. Lipsky, J. Chem. Phys., 51, 3616 (1969); (b) M. S. Henry and W. P. Helman, ibid., 56, 5734 (1972); (c) J. H . Baxendale and J. Mayer, Chem. Phys. Lett., 17,458 (1972). (17) W. A. Cramer, J. Phys. Chem., 71, 1171 (1967). (18) R. G. Adler and M. F. Hawthorne, J. Amer. Chem. Soc., 92, 6174 (1970), and references cited therein. (19) F. A. Matsen in "Chemical Applications of Spectroscopy," Vol. IX of "Technique of Organic Chemistry," A Weissberger, Ed., Interscience, New York, N. Y., 1956, pp 647-654. (2) (3) (4) (5)
Solvated Electrons in Alcohol-Alkane and Alcohol-Amine Solutions J. R. Brandon and R. F. Firestone* Department of Chemistry, The Ohm State University, Columbus, Oh/o 43210 (Recelved September 17, 1973) Publcahon costs assisted by the U S atom^ Energy Commmmn
The absorption spectrum of the solvated electron formed by pulse radiolysis of soIutions of ethanol in 3methylpentane, 2,2-dimethylbutane, and neopentane is unaffected by the presence of these alkanes above a few mole per cent of ethanol at room temperature. Above about 20 mol % solvated electron yields per unit of absorbed energy increase in the same order as the radiolytic free-ion yields of the pure alkanes. Below about 10 mol 70this order is reversed and the half-time for decay of the solvated electron at constant solution composition also decreases with increasing extent of chain branching in the alkane constituent. Similarly, the solvated electron yield in dilute solutions of methanol, ethanol, and cyclohexanol in neopentane decreases with increasing hydrocarbon character of the alcohol constituent. In ethanolethylenediamine solutions the amine is, to the contrary, the dominant solvating agent. These observations are discussed in the context of preferential solvation of excess electrons by microscopic aggregates of alcohol molecules and destabilization of these aggregates by alkanes and ethylenediamine.
Introduction The absorption spectra and the nature of solvated electrons in polar solvents and in binary liquid solutions of polar solvents appear to be determined principally by bulk solution properties.la Recent studies of the pulse radiolysis of alkane-alcohol solutions suggest, on the other hand, that electron solvation in solutions of polar molecules in nonpolar solvents at room temperature may, in some instances, occur entirely in polar molecule aggregates. Brown, Barker, and Sangster4 have observed that The Journalof Physical Chemistry, VoI. 78, No. 8, 1974
the absorption spectrum of the solvated electron is essentially the same in solutions containing as little as 5 mol 70 of ethanol in n-hexane as in pure ethanol.5 Similarly, Kemp, Salmon, and Wardman6 have found that the lifetime of the solvated electron in methanol is unchanged by the presence of 96 mol % of cyclohexane. Hentz and Kenney-Wallace7 have reported that E,,, is, however, detectably smaller in more dilute solutions of several normal alcohols in cyclohexane than in the pure alcohols. Optical absorption studies of the behavior of solvated electrons in such binary solutions will, hopefully, lead t o
793
Solvated Electrons in Alcohol-Alkane and Alcohol-Amine Solutions better understanding of the structure of markedly nonideal solutions as well as to improved insight into the nature of solvated electrons, per se. Therefore, we have begun a systematic study of effects of molecular structure of alkanes, alcohols, and amines on solvated electron spectra, yields, and decay kinetics in binary liquid solutions of these constituents. We have observed the solvated electron in solutions of ethanol with 3-methylpentane, 2,2-dimethylbutane, and neopentane, in solutions of methanol, ethanol, and cyclohexanol with neopentane and in solutions of ethanol with ethylenediamine. These alkanes have been selected because they facilitate study of effects of chain branching in the alkane constituent and exhibit a, perhaps, fundamentally significant correlative increase in the radiolytic free-ion yield and in electron mobility with increasing extent of chain branching. We report here some interesting effects of alkane structure on spectra and on the alcohol concentration dependence of solvated electron yields and the lifetime of the solvated electron. Some preliminary observations of the interestingly different behavior of solvated electrons in ethanol-ethylenediamine solutions are also presented. Experimental Section Phillips Research Grade alkanes were purified by washing with concentrated sulfuric acid and with water. This material was dried with LiAlH4 or phosphoric anhydride and stored in the absence of light. U. S. Industrial Chemical Co. ethanol was distilled from sodium ethoxide solution under nitrogen, outgassed, and stored in vacuo. Baker Reagent Grade methanol was purified by distillation from sodium methoxide solution. Baker Reagent Grade cyclohexanol was used without further purification. Baker Reagent Grade ethylenediamine was distilled after refluxing over potassium metal in a nitrogen atmosphere, outgassed, and vacuum distilled onto a potassium mirror. Information concerning the Ohio State University linear electron accelerator (Varian Assoc., V7715-A Linac) has been published previouslys.9 as has a description of the optical detection equipment.8.9 Single pulses of 3-4-MeV electrons of 10-80-nsec duration were used, except where otherwise indicated. Precise dosimetry was not needed for this study, but an 80-nsec 600-mA pulse is known to deliver a dose of approximately lo1' eV/g in water. The analyzing light source was a pulsed Osram XB0450W xenon discharge lamp, and the time constant of the detection system was approximately 6 nsec. All measurements were made at room temperature. Results Solvated electron absorption spectra are presented for ethanol in 3-methylpentane, 2,2-dimethylbutane, and neopentane in Figures 1, 2, and 3, respectively. These data and additional data covering a broader spectral range fit a Gaussian form at wavelengths below ,A,, and a Lorentzian form at wavelengths greater than A.,, Best fit values of bandwidth a t half-height (energy scale) have been found to be constant and independent of E,,, (photon energy a t A), without exception, including solutions in which E,,, shifts with dilution by alkane, Le., below 3 mol % of ethanol in 3-methylpentane (Figure 1).It has been observed previously that the product of bandwidth (cm-l) a t half-height and the molar extinction coefficient is given by a single constant in a variety of pure solvents and binary solutions a t room temperature .I J O Assuming
3- METHYLPENTANE SOLVENT
0.014
cz
-
0.010-
In n w -t
a
9 P +
0
1
0.002
.
I
I
I
0.6
I
I
1.0
0.8
x (B
Figure 1. Spectrum of the solvated electron at 1 , 2, and 3 mol % of ethanol in 3-methylpentane. 2,2 DIMETHYL BUTANE SOLVENT
i
0.020
>-
5
0.016
w z n -J
u k0
0.012
a
'
I
0.6
I
0.8
x (r,
1
I
I
I .o
Figure 2. Spectrum of the solvated electron at 3, % of ethanol in 2,2-dimethylbutane.
4,
and 5 mol
in the absence of contrary evidence that this product is invariant with respect to composition in alcohol-alkane solutions, the observed constancy of the bandwidth at half-height indicates that measured absorbance values divided by those observed in pure ethanol subjected to identical electron pulses are directly proportional to solvated electron yields per unit of absorbed energy. Figure 4 presents initial solvated electron yields for three ethanol-alkane solutions normalized to a value of unity for that in pure ethanol; reported values of the absolute yield in pure The Journalof Physical Chemistry, Vol. 78, No. 8, 1974
794
J. R . Brandon and R. F. Firestone NEOPENTANE SOLVENT
0.03
-
2.
5 z 0.020
-1
a 0
-
t
0
0.5
0.7
x (P)
0.9
0.01
-
-
13% 9%
0.7
0.0
0.9
h u
0001 00
Spectrum of the solvated electron at 6, 9, 13, and 18 ethanol in neopentane and the relative optical density (observed value divided by that for pure ethanol) at 7.6 and 10 mol % of ethanol in neopentane.
Figure 3. mol % of
0.2 MOLE
I
IO 0
I
I
20 0 300 MOLE PERCENT ETHANOL
I
i
430
Figure 5. Decay half-time of the solvated electron relative to that in ethanol as a function of composition for solutions of ethanol in neopentane ( . 0 . . ) , 2,2-dimethylbutane (- - 0 - -), and 3methylpentane (-0-).
1.0
0.6
FRACTION ETHANOL
Initial yield of solvated electrons relative to that in pure ethanol as a function of composition for solutions of ethanol in neopentane (a),2,2-dimethylbutane ( O ) , and 3-methylpentane ( 0 ) . Figure 4.
ethanol vary from 1.0l1 to 1.7 electrons/100 eV12 at rmm temperature. Yield values reported in Figure 4 are measured values extrapolated to the time of the beginning of the electron pulse by assuming first-order decay during the pulse and a rate of formation during the pulse proportional to the electron beam current of the essentially square pulse. The decay of solvated electron absorption signals was observed to be of first order at all compositions in ethanol-alkane solutions. Observed half-lives for decay varied from sample to sample of purified ethanol, but were found to be independent of composition above about 30 mol % of ethanol in each solution and were observed to decrease rapidly with decreasing ethanol concentration below about 15 mol % in each case. At constant composition below 15 mol 7% of ethanol these half-times decreased in the order 3-methylpentane, 2,2-dimethylbutane, neopentane as shown in Figure 5. Concomitant with the observed decrease in half-time we observed a steady shift of, , ,X toward the infrared with decreasing ethanol concentration in 3-methylpentane (0.7, 0.8, 0.9, and >1.0 p at 6, 3, 2, and 1 mol %, respectively) consistent with Hentz and Kenney-Wallace's observations concerning dilute solutions of several normal alcohols in cyclohexane Definite spectral shifts were not observed in solutions of ethanol with 2,2-dimethylbutane and neopentane. The half-time for decay followed a similar trend with respect to composition in all three binary systems.
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The Journal of Physical Chemistry, Vol. 78, No. 8, 1974
MOLE FRACTION ALCOHOL
Initial yield of solvated electrons relative to that in the pure alcohol for solutions of methanol ( O ) , ethanol (O), and cyclohexanol (a)in neopentane. Figure 6.
Figure 6 shows observed variations in the solvated electron yield with respect to alcohol concentration in solutions of methanol, ethanol, and cyclohexanol in neopentane at room temperature. These data demonstrate that solvated electron yields in solutions with neopentane relative to those in the pure alcohols5 increase in the order cyclohexanol, ethanol, methanol at all solution compositions. Figure 7A shows that the solvated electron absorption spectrum in ethanol-ethylenediamine solution containing 56 mol % of ethanol is virtually indistinguishable from that in pure ethylenediamine.13 Figure 7B shows that at 90 mol % of ethanol the absorption spectrum is similar to that in pure ethanol but that A,, exhibits a red shift of ca. 100 nm. This figure also shows clearly that there is no detectable spectral shift with respect to time during the first microsecond following appearance of the signal. It has been observed, then, that (a) only the unperturbed alcoholated electron spectrum appears in alcoholalkane solutions, except at very low alcohol concentrations in 3-methylpentane, (b) the solvated electron yield increases with increasing extent of alkane chain branching
795
Solvated Electrons in Alochol-Alkane and Alcohol-Amine Solutions ETHANOL-ETHYLENEDIAMINE
1
A.56 mole - % E t O H
0.70.9
1.1 A b1
1.3
8. 90 mOle-O/EtOH
0.6
0.8
1.0
X(P)
Spectrum of the solvated electron in solutions of ethanol in ethylenediamine: A, ( 0 )pure ethylenediamine, this work; 0, 56 mol % ethanol; solid line is based on data taken from ref 12; B, 90 mol % ethanol; 0, immediately after the electron pulse; 0 1 psec after t h e electron pulse.
Figure 7.
over most of the miscible composition range, (c) in the alkane-rich region below approximately 15 mol % ethanol increasing extent of alkane chain branching correlates with progressively smaller electron yields and shorter decay half-times, (d) the effects of increasing alcohol chain length are similar to those of increased alkane chain branching, and (e) the dominant solvent in ethanol-ethylenediamine solutions is ethylenediamine rather than ethanol. Discussion Binary alcohol-alkane solutions are, as a rule, markedly nonideal at room temperature and typically exhibit positive heats of mixing and positive excess Gibbs free energies a t all c0mpositions.~4~5 Available data indicate that these quantities become less positive a t constant alkane chain length as the alcohol chain length increases14 and more positive at constant alcohol chain length as the alkane chain length increases.15J6 Spectroscopic and thermodynamic data strongly suggest17~8 that a solution of an alcohol in a nonpolar solvent consists of a mixture of hydrogen bonded species and that the extent of association among alcohol molecules in a given solvent at a given temperature is greater in solutions with hydrocarbons than other nonpolar s01vents.l~Thus, it is reasonable to conclude that alcohols exist predominantly as higher polymers in hydrocarbon s01utions.l~The observed behavior to date of solvated electrons in ethanol-alkane solutions can be rationalized satisfactorily within this context. We postulate that alcohol molecules exist predominantly in alkane solutions as associated aggregates which simply scavenge and solvate quasi free electrons. It is apparent that ethanol aggregates are sufficiently extensive at room temperature to solvate electrons identically in all detectable respects as in pure ethanol above about 15 mol %, because neither the shape nor location of the absorption spectrum nor the decay half-time of the solvated electron is sensitive to the nature of the host alkane above 15-20 mol % of ethanol. The 100-eV yield of solvated electrons increases, however, in proportion to the 100-eV free-ion yield characteristic of the pure host alkane, ie., in the order 3-methylpentane, 2,2-dimethylbutane, neopentane. The so-called radiolytic free-ion yields of these alkanes are 0.15, 0.30, and 0.86 ion pairs/100 eV, r e s p e c t i ~ e l y .The ~ ~ observed
correlation of the solvated electron yield a t a given ethanol concentration with increased chain branching in the alkane constituent above 20 mol % of ethanol appears, accordingly, to be attributable simply to a scavenging mechanism and previously observed variations of the free-ion yield with respect to chain branching. At lower ethanol concentrations the order gradually reverses with decreasing ethanol concentration, because, we believe, of a probable correlation of the strength of ethanol-alkane interactions with increased chain branching, as discussed below. Variations of solvated electron yields with respect to concentration in solutions of methanol, ethanol, and cyclohexanol in neopentane (Figure 6) correlate with variations in hydrogen bond strength in these alcohols (methanol > ethanol > cyc1ohexanol)ls and with observed trends of heats of mixing and excess thermodynamic properties with respect to alcohol chain length.15-lT Less positive AHmlxlngand AGE values correlate with stronger interactions among unlike molecules, longer alcohol carbon chains, and generally increased hydrocarbon character of the alcohol constituent. Observation that solvated electron yields at constant concentration (Figure 6) decrease in the order methanol, ethanol, cyclohexanol in nrsopentane solutions is consistent with these thermodynamic trends and suggests that such data may be interpreted as measures of the abilities of the alkane molecules to destabilize electron scavenging alcohol aggregates. The behavior of solvated electron yields and decay halftimes in solutions of ethanol with 3-methylpentane, 2,2dimethylbutane, and neopentane below ca. 20 mol 70 of ethanol (Figures 4 and 5) suggests that the ability of the alkane constituent to destabilize ethanol aggregates increases markedly with increased chain brmching in the alkane constituent. Heats of mixing and excess thermodynamic properties are not available for these solutions. Solubilities follow generally similar trends, however, and increase in the order 3-methylpentane, 2,2 dimethylbutane, neopentane a t room temperature. It is likely, therefore, that the order of increasing strength of unlike molecule interactions and the order of decreasing stability of ethanol aggregates is that of increasing alkane chain branching. It, therefore, appears that the rates of change of yield and decay half-time of the alcoholated electron with respect to ethanol concentration below ca. 20 mol % are measures of the stabilities of ethanol aggregates in alkane-rich solutions. Interpretation is, however, complicated by the fact that the free cation yields also increase in the order of increasing alkane chain branching. Thus, it is possible that the destabilizing effect which is absent at higher ethanol concentrations induces some change in the relative importance of cations and ethanol molecules (CzH50H + esolCzH50 H)as agents for removal of the solvated electrons in the alkane-rich region. The contrasting behavior of solvated electrons in ethanol-ethylenediamine solutions relative to ethanol-alkane solutions is consistent wit,h the observation20 that AGE is strongly negative for solutions of short-chain primary amines in primary alcohols. Thermodynamic evidence of stronger than ideal attractive interactions between such constituents correlates with a virtual absence of ethanol aggregates below about 90 mol % of ethanol, as suggested by our observations. Thus, even though ethylenediamine is markedly less polar and solvates electrons less strongly than ethanol, it functions as the dominant solvent because of its ability to prevent formation of ethanol aggre-
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Augustine 0. Allen and Richard A. Holroyd
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gates. Conversely, preliminary findings suggest that effects of the presence of ethanol on the behavior of solvated electrons in amine-rich solutions is much less definitive. It has been observed2I that ethylenediamine is an extremely effective inhibitor of the decay of aromatic radical anions (ArCaH50H ArH C ~ H S O - in ) ethanol below ca. 68 mol % of ethanol, suggesting2I existence of a distinctive (2:1) hydrogen bonded ethanol-ethylenediamine complex. This and the present work suggest that the electron solvating mechanism in ethylenediamine is, relative to that in ethanol, quite insensitive to the presence of ethanol-ethylenediamine complexes. This may be an indication that nonspecific long-range electron-solvent interactions predominate in ethylenediamine and in ethylenediamine-rich solutions.
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I . A. Taub, M. C. Sauer, Jr., and L. M. Dorfman, Discuss. Faraday SoC., 36, 206 (1963); M. C. Sauer, Jr., S. Arai, and L. M. Dorfman, J. Chem. Phys., 42, 708 (1965). T. J. Kemp, G. A. Salmon. and P. Wardman, "Pulse Radiolysis,'' M. Ebert, et a/., Ed., Academic Press, London, 1965, pp 247-258. R. R. Hentz and G. Kenney-Wallace, J. Phys. Chem., 76, 2931 (1972). M. S. Matheson and L. M. Dorfman, "Pulse Radiolysis," MiT Press, Cambridge, Mass., 1969. L. M . Dorfrnan and J. M . Richter, "Ultrafast Processes," P. M . Rentzepis and J. Jortner, Ed., Plenum Press, New York, N. Y . , 1972. F. Y . Jou. private communication. I. A. Taub, D. A. Harter, M. C. Sauer, Jr., and L. M. Dorfman, J. Chem. Phys., 41, 979 (1964). K. M. Jha, G. L. Bolton, and G. R. Freeman, J. Phys. Chem., 76, 3676 (1972). J. L. Dye, M. G. DeBacker, and L. M. Dorfman, J. Chem. Phys., 5 2 , 6251 (1970). R. S. Ramalho and M. Ruel, Can. J. Chem. Eng., 46, 456 (1968). H. C. Van Ness, C. A. Soczek, and N. K. Kochar, J. Chem. Eng. Data, 1 2 , 346 (1967). C. G. Savini, D. R. Winterhalter, and H. C. Van Ness, J. Chem. Eng. Data, 1 0 , 168, 171 (1965). T. S. S. R. Murty, Can. J. Chem., 48, 184 (1970). G. C. Pimentel and A. L. McClellan, "The Hydrogen Bond," W. H. Freeman, San Francisco, Calif., 1960. W. H. Schmidt and A. 0. Allen, J. Chem. Phys., 50, 5037 (1969); 52, 2345, 4788 (1970); P. H. Tewari and G. R. Freeman, ibid., 49, 4394 (1968); P. G. Fouchi and G. R. Freeman, ibid., 56, 2333 (1972); R. M. Minday, L. D. Schmidt, and H. T. Davis, J. Phys. Chem., 76, 442 (1972). 8. K. Krichevtsov and V . M: Komarov, Zh. Prikl. Khim. (Leningrad), 43, 703 (1970). J. R. Brandon and L. M. Dorfman. J. Chem. Phvs., 53. 3849
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Acknowledgment. The authors are grateful for partial support of this work by USAEC Contract No. At-(ll-1)1116. References and Notes (1) 1.. M. Dorfman and F. Y. Jou, "Electrons in Fluid Media," J. Jortner, Ed., Hanita, Israel, June 1972. (2) A. Habersbergerova, I . Janovsky, and P. Kourim, Radiat. Res. Rev., 4, 123 (1972). (3) G. R. Freeman, J. Phys. Chem., 77, 7 (1973). (4) 8.J . Brown, N. T. Barker, and D. F. Sangster, J. Phys. Chem., 75, 3639 (1971).
Chemical Reaction Rates of Quasi Free Electrons in Nonpolar Liquids Augustine 0. Allen* and Richard A. Holroyd Chemistry Department, Brookhaven National Laboratory, Upton, New York 119.73 (Received September 9, 7973) Publication costs assisted by Brookhaven National Laboratory
A method is described for determining reaction rates of molecules dissolved in nonpolar liquids with electrons produced by ionization of the solvent. It is based on modification by the added substance of the current-growth curve which is seen when the liquid, in an electric field, is suddenly exposed to X-rays, and which is used for mobility determination by the Hudson method. The rate constants for recombination of electrons with positive ions, determined by the Langevin method in n-pentane, n-hexane, and tetramethylsilane, are diffusion controlled and hence proportional to the electron mobilities; this rate constant in tetramethylsilane is 5 x 1016 M - I sec-1. The electron reactions with CC11, CHJI, and 0 2 are not diffusion controlled; the rates are generally higher in solvents which show higher electron mobilities, but the increase is less than proportional. Different behavior is shown with C2HbBr; the electron reaction rate is lower in the high-electron-mobility solvents neopentane and tetramethylsilane than in hexane or 2,2,4-trimethyIpentane, and its temperature coefficient, which is positive in hexane, becomes unexpectedly negative in the former solvents, and amounts to -1.7% per degree in neopentane. New electron mobility determinations are reported for methylcyclohexane, n-hexane, n-pentane, cyclohexane, neopentane, and tetramethylsilane. Intraduction The mobility of electrons in liquid hydrocarbons has been widely studied recently,l-5 and varies greatly from one hydrocarbon to another; the mobility in neopentane is several hundred times greater than in normal pentane. The temperature coefficient of the mobility is positive and is larger in the lower mobility liquids, which suggests6 The Journal of Physical Chemistry, Voi. 78, No. 8, 1974
that the electrons are thermally activated from a trapped or solvated state, where their mobility may be no greater than that of ordinary ions, into a quasi-free state resembling the high-mobility condition seen in liquid argon. In pulse radiolysis of several hydrocarbons,',s absorptions in the infrared are seen which are attributed to these trapped or solvated electrons.
