Eley−Rideal Dynamics of the Chlorine Atom Abstraction of Hydrogen Chemisorbed on Silicon

Abstract

The reaction probability and product-state energy distribution in the Eley−Rideal reaction of gas-phase atomic chlorine with hydrogen atoms chemisorbed on a silicon surface are studied by use of the classical trajectory approach. Our model for study is based on reaction zone atoms interacting with a finite number of primary-system silicon atoms, which are coupled to the heat bath. At a gas temperature of 1500 K and a surface temperature of 300 K, all reactive events occur on a subpicosecond time scale as a result of efficient energy flow from the gas atom to the adatom−surface bond. These events are localized around the adatom site on the surface. Most of the reaction exothermicity is deposited into the translational and vibrational motions of HCl, producing a non-Boltzmann distribution. The reaction probability increases rapidly as the gas temperature is raised from 300 to 1000 K, above which it remains nearly constant at about 0.18. All product molecules leaving the surface undergo a cartwheel-like rotation.