Semiclassical Calculation of the Photodetachment Cross Section of Hydrogen Negative Ion Inside a Square Microcavity

The effect of a square microcavity on electron photodetachment from a hydrogen negative ion is studied on the basis of a semiclassical closed orbit theory for the first time. The classical motion of a photodetached electron is investigated and the total photodetachment cross section of this system is calculated. It is shown that the microcavity induces significant oscillations in the photodetachment cross section owing to the interference effects of the electron wave traveling along closed orbits. The oscillatory structure in the photodetachment cross section sensitively depends on the laser polarization and the position of negative ions. Each peak in the Fourier-transformed photodetachment cross section corresponds to the length of one closed orbit. As a demonstration, the two cases of a negative ion lying at the vertex of the square and in the middle of the square are calculated and analyzed in detail. We hope that our results will be useful in understanding the photodetachment of negative ions or electron transport in a microcavity.