Diffusion of metastable atoms and optovoltaic effect

Abstract

It was found that metastable atoms diffusing in a parent gas and bombarding a metal electrode, will cause an electric charge to build up on the electrode. Laser resonant pumping of a transition with a metastable lower level will cause depletion of the metastable atom density that, consequently, alters the electrode potential. It has been shown that in the case of neon, 1s5 metastable atoms are predominantly responsible for appearance of the optovoltaic (OV) signal that is defined as a potential difference between two electrodes equidistant from the discharge. By the laser induced fluorescence method a stationary distribution of metastables, produced by a discharge and diffusing into a neutral gas, has been measured. The results are supported by a model. Dependence of the OV signal on the position of the laser beam between the discharge and one of the electrodes has also been measured and a physical model developed.