Effect of temperature on the solvated electron in 1-propanol

Abstract

The technique of pulse radiolysis has been used to study the effect of temperature on the solvated electron in 1-propanol. The spectrum of the solvated electron has been measured in the range 140–298 K. The wavelength at maximum absorption, λ_max, decreases with decreasing temperature (corresponding to an increase in the energy, E_max) but the spectral width at half height, $\text{ΔE}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, changes little with temperature. At temperatures above ≈180 K, the formation of the solvated electron is complete at the end of the pulse and its spectrum shows no change in shape with time. Below ≈170 K, the absorption spectrum is time-dependent in both liquid and glassy phases, the changes being attributed to the solvation process. The reaction(s) leading to solvated electron formation following the pulse show an activation energy of 22±2 kJ mol⁻ and the solvated electron decays with an activation energy of 20±2 kJ mol⁻¹. The yield of solvated electrons decreases continuously with decreasing temperature in the range 298-77 K and, at all temperatures studied, is less than the total ionization yield measured by scavenging techniques.