Dynamics of Solvated Electron Transfer in Thin Ice Film Leading to a Large Enhancement in Photodissociation of CFCl₃

Abstract

Solvation and transfer dynamics of photoinjected electrons in thin ice film coadsorbed with CFCl3 were investigated by two-photon photoemission spectroscopy. Water molecules were found to solvate the photoinjected electrons within the first several hundred femtoseconds, thus stabilizing the electron with a lifetime of ca. 120 fs for 5 ML ice film grown on Ag(111). The significant lifetime decrease upon adsorption of CFCl3 on the ice film was attributed to dissociative electron transfer of the solvated electron based on the observed scission of the C-Cl bonds. Furthermore, the photodissociation rate of CFCl3 adsorbed directly on Ag(111) was observed to increase drastically owing to the transfer of the solvated electron when ice film was overlaid.

Cosmic-ray-driven electron-induced reactions of halogenated molecules adsorbed on ice surfaces: Implications for atmospheric ozone depletion and global climate change

“…The measured DEA cross section of gaseous CF 2 Cl 2 (Eq. (1)) at near 0eV is ~1x10 16 cm 2 , which is four orders of magnitude higher than the photodissociation cross section [32]. Immediately, Peyerimhoff and co-workers [33,34] made the first theoretical studies of the DEAs of CFCs and pointed out that this process must be considered as a mechanism for the destruction of CFCs and the ozone layer in the stratosphere.…”

“…In 2000s, Researches on electron solvation dynamics and associated dissociative electron transfer reactions of halogenated molecules have continued in water solution [21,[27][28][29][58][59][60][61][62], ice surface [63], ultrathin ice films [16,17,[64][65][66][67] and H 2 O anionic clusters [68][69][70][71][72][73]. Prior to 2008, many experimental and theoretical studies gave very diverse lifetimes and physical natures of e pre states in liquid water [49][50][51][52][53][54][58][59][60][61][62].…”

“…1. This leads to strong resonances of anion states of Cl-, Br-and I-containing molecules with e pre that is weakly-bound at 1.5 to 1.0 eV [13,16,17,21,[27][28][29]. Thus, quite effective resonant DET can occur for organic and inorganic …”

“…With a different approach, Ryu et al [16] and Bertin et al [17] have also observed the DET reactions of CFCs adsorbed on H 2 O ice on a metal substrate by monitoring the dynamics of trapped electrons with fs time-resolved two-photon photoemission (2PPE) spectroscopy. As shown in Fig.…”

Temperature and Coverage Dependent Quasi-reversible Two-photon Photoemission of 1-phenyl-1-propyne on Cu(111)

“…[1][2][3][4][5][6] For a simple molecular electronic device consisting of a molecule sandwiching between two metal electrodes, a basic operation concept is a charge flow from one to the other electrode through the sandwiched molecule. 1,2 In the device, the electron and hole barrier heights are one of the most important factors determining efficiency.…”