Effects of air leaks on XeCl laser performance

The effects of traces of oxygen and nitrogen on the initial laser power and on the gas lifetime of a xenon chloride excimer laser have been studied. When present in atmospheric proportions, nitrogen is found to have the dominant deleterious effect. The reaction, under laser conditions, with HCl and H2 forming the benign precipitate NH+4Cl− is observed. With HCl injections, a N2 contaminated gas mixture is found to be ‘‘self‐purifying’’ over periods of ∼2×106 shots. The effects of O2 contamination can also be largely counteracted by HCl injections. Conversely, injection of HCl into an old, but not intentionally contaminated, gas mixture causes a decline in the laser power.