Photoionization dynamics of glycine adsorbed on a silicon cluster: "on-the-fly" simulations

Dynamics of glycine chemisorbed on the surface of a silicon cluster is studied for a process that involves single-photon ionization, followed by recombination with the electron after a selected time delay. The process is studied by "on-the-fly" molecular dynamics simulations, using the sem...

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Bibliographic Details
Published in:The Journal of chemical physics 2005-05, Vol.122 (18), p.184704-184704
Main Authors: Shemesh, Dorit, Baer, Roi, Seideman, Tamar, Gerber, R Benny
Format: Article
Language:English
Subjects:
ATOMIC CLUSTERS
CHEMICAL BONDS
CHEMISORPTION
ELECTRON-MOLECULE COLLISIONS
EXCITED STATES
GLYCINE
GROUND STATES
HYDROGEN TRANSFER
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
MOLECULAR DYNAMICS METHOD
PERTURBATION THEORY
PHOTOCHEMISTRY
PHOTOIONIZATION
SILICON
SIMULATION
TIME DELAY
TUNNEL EFFECT
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Summary:Dynamics of glycine chemisorbed on the surface of a silicon cluster is studied for a process that involves single-photon ionization, followed by recombination with the electron after a selected time delay. The process is studied by "on-the-fly" molecular dynamics simulations, using the semiempirical parametric method number 3 (PM3) potential energy surface. The system is taken to be in the ground state prior to photoionization, and time delays from 5 to 50 fs before the recombination are considered. The time evolution is computed over 10 ps. The main findings are (1) the positive charge after ionization is initially mostly distributed on the silicon cluster. (2) After ionization the major structural changes are on the silicon cluster. These include Si-Si bond breaking and formation and hydrogen transfer between different silicon atoms. (3) The transient ionization event gives rise to dynamical behavior that depends sensitively on the ion state lifetime. Subsequent to 45 fs evolution in the charged state, the glycine molecule starts to rotate on the silicon cluster. Implications of the results to various processes that are induced by transient transition to a charged state are discussed. These include inelastic tunneling in molecular devices, photochemistry on conducting surfaces, and electron-molecule scattering.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.1894052