ELECTRON HYDRATION DYNAMICS - SIMULATION RESULTS COMPARED TO PUMP AND PROBE EXPERIMENTS

Previous analysis of the computer simulation of the relaxation of energetic excess electrons in Liquid water (Keszei E.; et al. J. Chem. Phys. 1993, 99, 2004) has led to a detailed molecular level and kinetic picture of this process, including the presence of multiple pathways to the equilibrium ground state. In order to explore the validity of this view, simulation results are directly compared to two available data sets obtained experimentally via ultrafast absorption spectroscopy. The analysis is carried out, first, by convolution of the simulated instantaneous spectral response of the electron with an appropriate instrumental response function. The difference between the resulting data and the reported experimental observations is no larger than the difference between the two experimental data sets. It is further shown by separate analysis that the mechanism of relaxation apparent in the simulation is kinetically consistent with the available experimental data. It is pointed out that a number of available, and apparently different, hypotheses for the sequence of species present during electronic relaxation share key features with this mechanism. Taken together, these considerations support the validity of the microscopic processes evident in simulation and emphasize the limitations inherent in the analysis of the experimentally determined spectral dynamics.