at 215 K the optical spectrum of e-, shifted unsymmetrically towards higher energy the first 500 ns. Approximating the decay of the low energy side and the growth of the high energy side of the band as first order, the mean decay time at 0.5EA,,. (e-,) was T, = 160 ns and the mean growth time at E > E A ,~~ (e-5) was T, = 40 ns. The behavior in 1,3-butanediol (13BD) at 225 K was similar, with T~ = 170 ns at 0.5EAm,, and T , = 40 ns at E > EAmax. The solvation time constant T, is only slightly greater than 7,. The larger value of T~ is caused by replenishment of the state at 0.5EA,,, by relaxation from lower energy states. In all diols at T 2 240 K (2298 K for 14BD) the spectra reached their equilibrium shape within 150 ns after the start of the 100 ns radiation pulse. The value of EAm, , of e-, in the 1 ,2-diols is -0.1 eV greater than those in the other diols and 0.2-0.3 eV greater than that in a primary alcohol at the same temperature. In the secondary-secondary diol 23BD at 296 K, EAmnx is 0.6 eV greater than that in 2-propanol. The vicinal diol part of the molecule dominates the intermolecular solvation site of the electron. The temperature coefficient (-dE~,,,ldT) increases from 2.6 meV/K in 12 ED to 3.6 meV/K in 23BD. The asymmetry factors Wb/Wr of the e-, bands in the diols are 1.6-2.1, somewhat lower than those in the analogous alcohols, 1.9-2.4. The values of W, are similar, 0.54 k 0.04 eV, in all the diols, independent of T, with Wr/EA,,, = 0.24 + 0.02; dWb/dT < 1.0 meV/K. The value of (GE),,, has an upper limit of -2.5 X lo4 e-,/lo0 eV M cm in the low temperature liquid diols. The value of go^,,, is 1.2 X lo4 in all diols except 23BD, in which it is 1.3 x lo4, independent of T. Dans le propanediol-1,2 (PD12), a 215 K, le spectre optique des e-, glisse d'une faqon non symCtrique vers les hautes Cnergies pendant les 500 premikres nanosecondes. En faisant I'hypothkse que la dCcroissement du c8tC de faible Cnergie et que la croissance du cBtC de haute Cnergie de la bande sont d'ordre un, le temps moyen de dCcroissement a 0,5EA,,, (e-,) est T, = 160 ns et le temps moyen de croissance a E > E, , . , (e-,) est de T , = 40 ns. A 225 K, le butanediol-1,3 (BD13) se comporte de la m&me faqon et T, = 170 ns a 0,5EA,,, et T , = 40 ns a E > EAmax La constante de temps de solvatation T, n'est que 1Cgkrement sup6rieure a 7 , . La valeur plus ClevCe de T , est due au remplissage de 1'Ctat a 0,5EA,,, par une relaxation des Ctats de plus faible Cnergie. Dans tous les diols, a des T 2 240 K (2298 K pour le BD14), les spectres atteignent leur forme d1Cquilibre en moins de 150 ns aprks le dCbut de la radiation pulsCe de 100 ns. A des tempCratures constantes, la valeur de EAmax des e-,, dans les diols-1,2, est sup6rieure d'environ 0,l eV a celles observCes avec d'autres diols et de 0,2 0,3 eV sup6rieure a celle observke dans un alcool primaire. Dans le diol secondaire-secondaire (BD23), a 296 K, la valeur de E,,,, est de 0,6 eV sup6rieure a celle observke dans le propanol-2. La portion viccinale de la molCcule de diol domin...

Investigation of the effect of solvent structure on the optical absorption spectrum and reactivity of solvated electrons has been extended to diol/water mixed solvents, using 1,2-ethanediol (12ED) and 1,4-butanediol (14BD). The large effects that had been found in mono-ol/water mixed solvents did not occur in diol/water. Although addition of 3 mol% of a diol to water increased the optical absorption energies of e−s by 0.06 eV, similar to the shift caused by addition of 3 mol% of a mono-ol, the variation of the spectrum over the rest of the composition range was nearly ideal in diol/water, in contrast to the very non-ideal variation in mono-ol/water. Reaction rate constants kS at 298 K in the diol/water mixed solvents vary approximately as the inverse viscosity,η−1.0, in the diffusion-controlled limit. However, when reactions are two or three orders of magnitude slower than diffusion controlled, kS at 298 K is independent of η. Toluene reacts with e−s at a 10−3-fold smaller rate than does nitrobenzene; the difference is nearly completely due to a ~50 J/mol K lower entropy of activation of the former reaction.

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