XENON LUMINESCENCE IN HIGH-PRESSURE ARGON - SPECTROSCOPY AND KINETICS

The luminescence associated with selective excitation of the three lowest xenon resonant levels (P-3(1)/6s[3/2]1(0), P-1(1)/6s'[1/2]1 and 5d[3/2]1(0)) in high pressure (14-71 bar) argon doped with minimal amount of xenon is reported. Under these conditions the decay channels specific to Xe*Ar were obtained without Xe2* formation. In particular, it is demonstrated that the part of the P-3(1) level excitation population which is not radiated ''immediately'' is first transferred to the P-3(2) metastable level. Subsequently a long P-3(1) decay also occurs via its formation by the reverse reaction. An analogous behavior is found for the upper P-1(1)/P-3(0) levels showing that most of the fluorescence is retarded with in this case transfers of population to the close 6p[1/2]1 and to 6s(P-3(1)/P-3(2)) levels. The behavior found after 5d[3/2]1 level excitation is quite different, with in parallel a fast direct fluorescence and a quenching into the P-1(1)/P-3(0) levels but not directly into the P-3(1)/P-3(2) levels. A kinetic analysis is developed according to these schemes. Particularly, the P-3(1) to P-3(2) quenching is found to depend linearly on the density with the rate k2 = (4.5 +/- 0.5) X 10(-13) cm3 s-1. The more complicated description of the P-1(1) clearly indicates the necessity of using selective excitation to succeed in a self-consistent interpretation.