Selective subsurface absorption of hydrogen in palladium using laser distillation

Abstract

A theoretical model for the selective subsurface absorption of atomic hydrogen in a Pd(111) surface by infrared (IR) laser pulses is presented. The dynamics of the adsorbate is studied within the reduced density matrix approach. Energy and phase relaxation of the hydrogen atom are treated using the semigroup formalism. The vibrational excitation leading to subsurface absorption is performed using rationally designed pulses as well as IR laser pulses optimized on-the-fly. It is shown that dissipation can be used as a tool to transfer population to an otherwise inaccessible state via a mechanism known as "laser distillation." We demonstrate that when the reaction path is generalized from a reduced one-dimensional to full three-dimensional treatment of the system, the laser control strategy can prove very different.

Diffusion Rates for Hydrogen on Pd(111) from Molecular Quantum Dynamics Calculations

“…These sets arise from the tunneling splitting of degenerate vibrationally excited levels and remaining degeneracies are indicated by the numbers in parentheses. In refs [17] and [18], only one value is reported per transition. The present results for vibrational wavenumbers are comparable to the previously reported values.…”

“…Note that the kinetic energy operator contains non-diagaonal terms, when such coordinates are used [17]. For this three dimensional study, the analytical PES from [6] was first modified such as to describe a single hydrogen atom adsorbed on the palladium substrate.…”

Electronic damping of anharmonic adsorbate vibrations at metallic surfaces

“…The dipole moment function was obtained from cluster model calculations using density functional theory. 23 In the case studied here, the dynamics follows the direction perpendicular to the surface. Furthermore, the component of ͑p͒ parallel to the surface is small in comparison to the perpendicular one.…”

Ab Initio Molecular Dynamics Simulations of the Adsorption of H2 on Palladium Surfaces

“…In addition, comparisons between six-dimensional quantum and classical calculations showed that the role of quantum effects in the hydrogen adsorption dynamics on surfaces is limited. [51,50] A coupling to phonons and electron-hole pairs has been considered in quantum mechanical studies addressing the subsurface adsorption of hydrogen, [16,52,53] but these calculations were performed in a lowdimensional framework.…”