Discharge Pumped Rare-Gas Excimer Lasers in Vacuum Ultraviolet Spectral Region

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Rare gas excimer lasers are atractive vacuum ultraviolet sources with high power tunable output around the center of their spectra. However, their oscillation have been obtained only by electron beam pumping. The electron beam pumped rare gas excimer lasers have difficulties for applications because of their low repitition operation. It, therefore, has been desired the rare gas excimers were considered to produce by three body collisions of an excited rare gas atom with two of ground state atoms. In this case a high pressure operation is favorable, because a formation rate of raer gas excimers is proportional to the square of the gas pressure. It is well known that uniform glow discharges in the high pressure gas are very difficult to establish. We have proposed a new concept of formation of the rare gas excimers in which the rare gas excimers were formed from rare gas clusters in an expanding jet discharge.In this project it has been experimentary confirmed that Xe excimers were forme … More d from the Xe clusters excited by discharge electrons. Distributions of sizes of the Xe clusters were measured with a TOF spectrometer by three photon ionization of the clusters. Densities of the Xe dimers were measured to be 10^<17>cm^<-3> at 3mm down stream of the expanding jet with 3atm.to 8atm.of staggnation pressures. Densities of Xe excimers were measured to be 10^9cm^<-3>, the densities of the clusters were 10^<17>cm^<-3> though. These very low efficiency of excimer formation from the clusters is considered to be unsuitable discharge conditions.In DC sischarges radiative transitions from the ^3SIGMA excimer state were predominant, stimulated emissions, therefore, were not observed because the stimulated emission cross section of ^3SIGMA state was three orders smaller than that of ^1SIGMA state. As a result it is considered that fast pulsed discharges should be essential for obtaining a high laser gain.It is very important to point out that an efficinet vacuum ultraviolet lamp can be produced using the excimer radiation by the ^3SIGMA transitions.In future electron energy dependences of the excitation cross sections of rare gas excimers from the clusters will be measured in order to conclude efficient discharge conditions. Less