A pulse radiolysis study of electrons in 1-propanol at low temperatures

Previous observations on the spectral changes due to electrons in 1-propanol have been extended to 77 K. It is found that down to 118 K the decay in the I.R. and growth in the visible are first order and that from 118 to 313 K the rate constants fit the modified Arrhenius expression of Tamman and Hesse, as do the relaxation times obtained from dielectric dispersion measurements and the alcohol viscosity. These changes are considered to arise from molecular reorientation around the electrons. Below 118 K, the kinetics are no longer first order, the changes are much more extended in time and are also much faster than expected from an extrapolation of the observations at the higher temperatures. Electron loss, presumed due to ion recombination, also occurs. It is concluded that the mechanism responsible for the spectral shifts is different at these lower temperatures and that here thermal excitation from shallow traps and retrapping by deeper ones occur. (author)