Application of closed-orbit theory to the Rydberg hydrogen atom near a metal surface

Abstract

Using closed-orbit theory, we study the classical motion and calculate the photoabsorption spectra and recurrence spectra of the Rydberg hydrogen atom near a metal surface. The results show that when the atom–surface distance is close to the critical value dc, the number of the closed orbits is the greatest. For d > dc, with the increase of the distance d, the number of the closed orbits decreases and the absorption spectra are shown to exhibit a damping oscillation. For d < dc, the electron can travel for a very short time before it has returned to the nucleus. At a smaller distance, some of the electronic trajectories can be absorbed onto the metal surface. In order to show the relation between the absorption spectra and the closed orbits, we calculate the Fourier transformed recurrence spectra of the Rydberg hydrogen atom near a metal surface by using the closed-orbit theory. Each resonance peak in the recurrence spectra is associated with one electron closed orbit. The agreement between the semiclassical calculation spectra and the quantum calculation spectra suggests that our analysis is correct. This study provides a different perspective on the dynamical behaviour of the Rydberg atom near a metal surface.