Effects of F6- ions and F2 molecules on the oscillation process of a discharge-pumped ArF excimer laser

Time-resolved number densities of the fluorine negative ion in a discharge-pumped ArF excimer laser are measured by a dye laser absorption method. The peak density of F- is 0.93 x 10(15) cm(-3) at a total gas pressure of 2.5 atm, a gas mixture ratio of F-2-Ar-He = 0.2-10.0-89.8, and a charging voltage of 28 kV for a 68-nF storage capacitor bank, The dependences of the peak F- density and the ArF laser output power on the F-2 gas fraction in Fz-Ar-He mixture are investigated, The effects of F- ions and F-2 molecules on the ArF laser oscillation process are discussed by considering the F-2 mixture-ratio dependences of particle densities, laser output power, mean electron energy, and laser power extraction efficiency, With increasing F-2 mixing ratio, the ArF* excimer formation first increases as F- increases, but in F-2-rich conditions the laser power decreases because of the laser photon absorption due to F- ions and quenching of ArF* with F-2 molecules.