Comparative study of the formation and decay of xenon excimers following selective excitation of the 5p⁵6s states: spectroscopic and kinetic analysis

Abstract

In order to specify the mechanisms involved in a xenon dielectric barrier excimer lamp, an experimental work was undertaken using two different set-ups. One study, performed under selective multiphotonic excitation, is presented here and the other, of a dielectric barrier micro-discharge, will be published in another paper. In this work, excitation of the two lower atomic states of the 5p56s configuration was performed: the Xe5p56s(3P2) metastable state and the molecular g states correlated to it or to the Xe5p56s(3P1) resonant state were excited by absorption of two photons. A spectroscopic and kinetic study was performed for the first time, comparing the radiation characteristics consecutive to initially populating either the resonant Xe5p56s(3P1) or the metastable Xe5p56s(3P2) states. A first continuum issuing from 1u state and broader than the 0+u one is observed. The transfer from the 0+u(3P1) state to a dissociative state correlated to Xe5p56s(3P2) is clearly shown. The sum of the transfer and relaxation rate constants was measured: kt + kv = (1.6 ± 0.5) × 106 Torr−1 s−1.

Temperature dependence of xenon excimer formations using two-photon absorption laser-induced fluorescence

“…Hence at 294 K, the molecular structure for wavelengths below the resonant state can be attributed to Xe 2 (B 1 g ), and absorption arises in the repulsive part of the ground-state potential (e. g. R ∼ 3.9Å). Excitation of Xe 2 B 0 + g occurs at shorter wavelengths with a maximum around 290.2 nm according to Ledru et al [14] and Gornik et al [30]. At high pressures, particularly above 100 Torr, for either any excitation condition or any gas temperature, the shapes of emission spectra are similar (fig 4).…”

“…In such conditions, recombination phenomena, electronic collisions or atomic collisions involving two excited species do not contribute to the formation and decay of excimers. According to the simplified kinetic scheme established in a previous work at room temperature [14] for the emission of the first continuum, after selectively populating the resonant state, the evolution of the concentration the different states is governed by the differential equations :…”

Measurements of Absolute Atomic Nitrogen Density by Two-Photon Absorption Laser-Induced Fluorescence Spectroscopy in Hot Air Plasma Generated by Microwave Resonant Cavity

“…Before being filled with pure krypton or a mixture of synthetic air and krypton, the cell was pumped down to full range of 1000 Torr for high pressure conditions. This experimental set-up has been fully described in a previous work [14].…”

Infrared emission spectrum and potentials of 0+uand 0+gstates of Xe2excimers produced by electron impact

“…The Franck-Condon simulation of the spectrum shape suggests that emission stems from a bound-free molecular transition never studied before. The states involved are assigned as the bound (3) Luminescence of rare gas excimers is studied for applications in the vacuum ultraviolet (VUV) [1]. It is worth recalling, for instance, the Xe-based high-energy particle detectors, in which the VUV scintillation light produced by the transit of an ionizing particle is detected [2].…”

“…The kinetics of the processes leading to excimer formation and VUV emission has been clarified in spectral and time resolved experiments, in which lifetimes and rate constants are determined [1,7,11,12,13,18,21,22,23,24,25,26].…”