Total photodetachment cross section of H− near a reflecting wall was studied recently by Yang et al using closed-orbit theory (2006 J. Phys. B: At. Mol. Opt. Phys. 39 1855). The main effect of a reflecting wall was shown to induce an oscillation in the cross section. In this paper, we study the photodetachment of H− near a reflecting wall using a theoretical imaging method, which is very different from the method of closed-orbit theory. The theoretical imaging method enables us to derive the total and differential photodetachment cross sections in a straightforward way. We considered both a soft wall case and a hard wall case, they differ by the values of phase loss when reflecting the detached-electron waves. The result of Yang et al for the total photodetachment cross section is the asymptotic limit of our formula for the soft wall case. We also calculated the detached-electron flux distributions on a screen placed at a large distance from the negative ion. The distributions display strong interference patterns. Such interference patterns are similar to those in the photodetachment microscopy experiments.

A theoretical imaging method is used to study the induced effects of a spherical surface on the photodetached electron spectra of a mono-atomic negative ion (H − ). Analytical formulas are derived for the detached electron flux and the total photodetachment cross section. The radius of the spherical surface strongly affects the spectra of the flux as well as the cross section. The analysis of the spectra reveals that the curvature of the surface controls the oscillations in the spectra, and the plane wall case reported in Afaq and Du (2007 J. Phys. B: At. Mol. Opt. Phys. 40 1309) is a special case of the spherical surface.

Structural and optoelectronic properties of BaThO3 cubic perovskite are calculated using all electrons full potential linearized augmented plane wave (FP-LAPW) method. Wide and direct band gap, 5.7 eV, of the compound predicts that it can be effectively used in UV based optoelectronic devices. Different characteristic peaks in the wide UV range emerges mainly due to the transition of electrons between valance band state O-p and conduction band states Ba-d, Ba-f, Th-f and Th-d.Comment: 20 pages and 7 figure

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