Time dependence of the vacuum-ultraviolet emissions in krypton excited by 250-KeV electrons

Abstract

Time-dependent studies of the vacuum-ultraviolet emissions in krypton were performed using 250-keV electrons. Measurements as a function of pressure were made at the wavelengths of the ${}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ and ${}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}$ resonance lines and the 1250- and 1425-Å continuum emissions. The suggest that at early decay times the ${}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}$ atomic state is responsible for the 1250-Å molecular radiation. From the time-dependent studies it is proposed that the ${}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ state is converted to a highly excited molecule by two-body collisions. This molecule undergoes rapid vibrational relaxation resulting from two- and three-body collisions. The vibrationally relaxed molecule then radiates the 1425-Å continuum. At high pressures (about 1000 torr) the vibrationally relaxed molecule decays with a nearly pressure-independent lifetime of about 0.30 μsec.