A Surrogate Hamiltonian study of femtosecond photodesorption of CO from NiO(100)

Abstract

In this paper, the Surrogate Hamiltonian approach is employed in order to study electronic relaxation in femtosecond laser-induced desorption experiments of CO from NiO(100). The study is based on ab initio calculations and a microscopic description of the NiO(100)-surface and the relaxation mechanism developed by Koch et al. The relaxation mechanism is assumed to be of dipole–dipole interaction nature, where the transition dipole moment of the adsorbate interacts with surface electron-hole pairs. In the Surrogate Hamiltonian approach the electron-hole pairs are treated as two-level systems and are described by excitation energy and a dipole charge. The Surrogate Hamiltonian parameters and potential energy surfaces used are obtained from ab initio calculations. The desorption probability and the velocity distributions of the desorbing molecules are calculated and an excited state lifetime is predicted. Throughout this paper atomic units, i.e. ℏ︀ = m _e = e = a ₀ = 1, have been used unless otherwise stated.

Keywords:

• photodesorption
• dissipation
• surface science
• CO
• Surrogate Hamiltonian
• NiO(100)

Acknowledgements

Financial support from Deutsche Forschungsgemeinschaft (Grant KL 1175-11-2) is gratefully acknowledged. All calculations have been performed on the High-End Computing Resource Oldenburg (HERO).