Energy transfer studies in krypton-xenon mixtures excited in a cooled DC discharge

The VUV spectrum of gaseous mixtures of krypton with a small amount of xeno n added was investigated in the range 115-200 nm. The mixtures were excited in a capillary DC discharge where the capillary could be cooled by using l iquid nitrogen. The mixed molecule band around the Xe I resonance line at l ambda = 147 nm and the mixed molecule continuum to the long wavelength side from the line were analysed. The band around lambda = 147 nm was identifie d as transitions between a weakly bound excited state and the weakly bound ground state of XeKr molecules. When cooling the capillary wall, the appear ance of the Xe-2 continuum was observed. The effect is ascribed to energy t ransfer between molecular states as a consequence of radiation trapping in the band around lambda = 147 nm. The role of the mixed molecule in the form ation of the VUV spectrum of the gas mixture is discussed and underlined.