Photodetachment of H− in the magnetic field near a metal surface

Using the closed orbit theory, we give a clear physical picture description of the photodetachment of H− in the magnetic field near a metal surface. The photodetachment cross-section of this system is also derived and calculated. It is found that the effect of the metal surface can be considered as a varying electric field. The detached electron's motion and the cross-section are similar to the case of the photodetachment of H− in parallel electric and magnetic fields. For a given ion-surface distance, the cross-section depends sensitively on the magnetic field strength. As the magnetic field strength is weak, the cross-section is the same as the photodetachment of H− near a metal surface. With the increase of the magnetic field strength, the number of the closed orbits increases and the photodetachment cross-section becomes much more complicated. This study provides a new understanding on the photodetachment process of negative ions in the presence of external fields and surfaces.