Absorption Line Profile of the Transition of Atomic Oxygen and Its Application to Plasma Monitoring

The line profile of the 52−51 transition of atomic oxygen was measured by diode laser absorption spectroscopy. As a result, it was found that the absorption line profile had a wing component in the wavelength range detuned from the line center and was not fitted with a Gaussian function. The wing component was considered to be originated from dissociative excitation ofmolecular oxygen. We fitted the absorption line profile with the superposition of two Gaussianfunctions corresponding to high and low translational temperatures. We propose that the ratio ofthe high-temperature to low-temperature components is useful for monitoring the relative degree ofdissociation of molecular oxygen in oxygen-containing plasmas. The ratio of the high-temperatureto low-temperature components was compared with the survival ratio of molecular oxygen, whichwas evaluated from the lifetime of O(52) in the afterglow of pulsed discharges