THE VACUUM-ULTRAVIOLET SPECTRUM OF KRYPTON AND XENON EXCIMERS EXCITEDIN A COOLED DC DISCHARGE

We present results of an experimental and theoretical study of the VUV spectra of krypton and xenon excimers excited by a de discharge in a capillary tube cooled by liquid nitrogen. The studied spectral regions of 115-170nm and 140-195 nm for krypton and xenon respectively corres pond to transitions between the lowest excited dimer states 1(u), 0(u) (+) and the weakly bound ground state 0(g)(+). A semiempirical method was suggested and applied to describe the experimental spectra and to estimate the temperature of the radiating plasma volume. Electron impa ct, transferring dimers from the ground state to the excited states, i s shown to be an efficient excitation mechanism in the 100-850 hPa and the 10-50 mA pressure and discharge current ranges. The spectra obtai ned as well as the results of calculations corroborate the high rate o f this mechanism.