Laser induced photo-detachment of O₂ in DC discharge

Determination of the negative ion number density of and in a DC discharge of oxygen plasma was made employing Langmuir probe in conjunction with eclipse laser photo-detachment technique. The temporal evolution of the extra electrons resulting from the photo-detachment of and were used to evaluate the negative ion number density. The ratio of number density to varied from 0.03 to 0.22. Number density of both and increased with increasing power and decreased as the pressure was increased. Electron number density was evaluated from the electron energy distribution function (EEDF) using the I–V recorded characteristic curves. Electron temperature between 2 and 2.7 eV were obtained. Influence of the metastable state is discussed.