The mechanism of electron thermalization in H2O, D2O, and HDO

The yield of the hydrated electron was measured as a function of time in H2O, D2O, and mixtures of the two solvents. The results of these measurements showed that the decay of eaq-, was considerably slower in D2O than in H2O. These results suggest that the electron travels a longer distance in D20 than in H2O. In H2O-D2O mixtures there had to be at least 50% D2O in the solution before the decay was appreciably different from the pure H2O solution. The decay in 80% D2O is still considerably different than the decay in pure D2 solution. From these results we draw the following conclusions. (i) The distance an electron travels before salvation is greater in D2O than in H2O. (ii) Much of the travel of the electron prior to thermalization occurs when the energy of the electron is less than the excitation energy of the solvent. (iii) A major mode of energy loss is due to energy transfer to the stretching vibrational modes of the water molecules. (author)