Thermalization of photoelectrons in polar medium

Abstract

The process of thermalization of a hot subexcitation photoelectron in polar medium is studied. The master equation is used as a starting point to derive analytic expression for the thermalization distances distribution function. The resulting expression depends upon the mechanism of energy dissipation via the first two moments of the energy loss probability. Asymptotic decay of the distribution with the distance depends on the character of electron motion (exponential for the ballistic motion; Gaussian for the diffusion). A general scheme was developed for evaluation of the energy loss probability within the framework of the linear response theory. Explicit results are derived for electron thermalization in polar medium whose dissipative properties are characterized by the Debye macroscopic dielectric susceptibility function (the Frohlich-Platzman model). Comparison of the estimates of thermalization distance in water with the experiment shows that the randomization of the direction of the electron motion is much faster than the thermalization process. The dependence of the most probable (average) thermalization distance on the initial kinetic energy, E in , and on the dielectric relaxation time, T D' is found for the ballistic and the diffusive motion of the electron ( 0:: E ~:4T }{2 for diffusive motion). An explicit relation is derived between the probability to escape geminate recombination and the excess kinetic energy as well as the polarity of the medium and its relaxation time. Results are used to interpret the recent experimental data on the yield and kinetics of geminate recombination in normal and heavy water.

The ejection distribution of solvated electrons generated by the one-photon photodetachment of aqueous I− and two-photon ionization of the solvent

“…For pure glycol, one would suspect that the lower ͗r 0 ͘, and hence the markedly lower escape fraction, is due to the different electron kinetic energy of electrons ejected from the ionized glycol molecule. 62 Energetic threshold data for ethylene glycol are not established that might suggest which ejection mechanism regime 45,53 is operative at 9.7 eV excitation.…”

“…45,58,62 The different distribution functions and their resultant time dependent survival probabilities are shown in Fig. 10.…”

Interfacial Speciation Determines Interfacial Chemistry: X‐ray‐Induced Lithium Fluoride Formation from Water‐in‐salt Electrolytes on Solid Surfaces

“…[38] Angewandte Chemie Research Articles 23184 www.angewandte.org water, 2.5 nm in ethanol, 20 nm in hexane,and approximately 1.5 nm in ionic liquids. [22] Timescales for thermalization are around tens of femtoseconds in water [23] and less than 1psin ionic liquids. [24] Ty pical solvation timescales are on the order of ps for traditional low viscosity solvents (water and organic), whereas for ionic liquids with much higher viscosity they can be on the order of hundreds of picoseconds to tens of ns; [25] here,weconsider neat water the extreme case of salt-in-water (i.e.nosalt), and we consider ionic liquids the extreme case of water-in-salt (i.e.n ow ater).…”

Interfacial Speciation Determines Interfacial Chemistry: X‐ray‐Induced Lithium Fluoride Formation from Water‐in‐salt Electrolytes on Solid Surfaces

“…[38] Angewandte Chemie Forschungsartikel 23384 www.angewandte.de water, 2.5 nm in ethanol, 20 nm in hexane,and approximately 1.5 nm in ionic liquids. [22] Timescales for thermalization are around tens of femtoseconds in water [23] and less than 1psin ionic liquids. [24] Ty pical solvation timescales are on the order of ps for traditional low viscosity solvents (water and organic), whereas for ionic liquids with much higher viscosity they can be on the order of hundreds of picoseconds to tens of ns; [25] here,weconsider neat water the extreme case of salt-in-water (i.e.nosalt), and we consider ionic liquids the extreme case of water-in-salt (i.e.n ow ater).…”