Kinetics of O(1S) and O(1D) metastable atoms in a DC oxygen glow discharge

Abstract

The concentrations of O(1D) and O(1S) metastable atoms are measured in the positive column of a DC oxygen glow discharge by vacuum ultraviolet absorption spectroscopy at 115 and 122 nm respectively. In the investigated range of pressures p=0.2-2 torr and discharge currents Id=10-80 mA, the concentrations of O(1D) and O(1S) atoms range from 1011-1012 and from 1010-1011 cm-3 respectively. In these conditions the main creation and destruction processes are discussed: the O(1D) atoms are created by electron impact dissociation of O2(X3 Sigma ) and O2(a1 Delta ), and excitation of O(3P), and lost through quenching by oxygen molecules. It is shown that it is necessary to add to the electron impact excitation another creation term of O(1S) atoms to balance the destruction through quenching by O2(X3 Sigma ), O2(a1 Delta ) and O(3P).