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.

The experimental work reported here is devoted to the temporal behaviour of a mono-filamentary dielectric barrier discharge in pure argon, from 100 to 700 Torr. A sinusoidal voltage supply is used, its frequency ranging from 10 to 90 kHz. An anode avalanche followed by a cathode streamer as well as the spatial stability of the micro-discharge is clearly seen in successive 3-ns snapshots in the visible range. Near the cathode, its diameter is about 0.2 mm, at 400 Torr. The electrical characteristics of the discharge are also evaluated, in particular the breakdown voltage and the energy deposited in the micro-discharge. The light output in the vacuum ultraviolet range is essentially due to the second continuum of argon, centred at 130 nm. The kinetic study of this continuum shows that primary excitation of the lowest argon atomic 4s and 4s′ states is practically achieved after 120 ns since beyond that time the luminescence decay of the second continuum is fairly described by only two exponential terms. So collisions between excited states, electronic collisions, and recombination of ionic species do not contribute significantly to this luminescence, after 120 ns. Surprisingly, we do not observe the contribution of the Ar(3P1) resonant state in the production of the argon excimers. The radiative lifetime of the Ar2[1u(3P2)]low v excimer ((3.18 ± 0.03) µs) and the three-body rate constant relative to the decay of the Ar(3P2) metastable state ((13.2 ± 0.9) Torr−2 s−1) leading to the formation of Ar2[1u(3P2)], are estimated. These results are consistent with those found from the literature. A simple kinetic scheme is proposed for times later than 120 ns.

Selective excitation of xenon by multiphoton absorption of a dye laser beam gives, in the VUV, the emissions characteristic of this gas, i.e., the resonance line at 147 nm, the first continuum at 150 nm and the second continuum at 173 nm. The kinetic analysis of these emissions was carried out, using a correlation method, between 10−2 and 600 Torr. At low pressures the temporal variation of the density of the resonant 3P1 states allowed the resonance line trapping phenomenon to be demonstrated and the natural lifetime of these states to be determined (τn =4.3 ns). At high pressures the metastable 3P2 states are involved in the emission of the second continuum. The excitation spectra plotted for the blue satellite showed the creation of states in the 4f configuration. This phenomenon indicates that multiphoton ionization is not responsible for the creation of the metastable states. These states are created from a crossing of two molecular levels, one of which is bound (0+u) and responsible for the first continuum and the other of which is dissociative (2u) and correlated to the 3P2 state.

The spectroscopic analysis of xenon at pressures between 50 and 700 torr shows the presence of several continuums over a wavelength range of 110–700 nm. The kinetics of two of them, 173 and 210 nm, are studied. In both cases, the shape of the light pulse, reconstituted by a time-amplitude conversion method, is defined by a difference of two exponential terms. These terms represent the formation and the decay of the molecular species. The variation of the time constants with pressure allows the reaction constants of the various processes in the kinetic scheme to be found. The continuum in the vuv is brought about by the 3Σ+u state formed by three-body collisions: k= (8.0±0.7)10−32 cm6 s−1 and the lifetime τ=102±2 ns; in the near uv, the molecular state has a shorter lifetime τ′1=8.2±0.5 ns but is formed like the previous one by three-body collisions: k3= (2.3±0.06)10−30 cm6 s−1. The near uv xenon emission constants ave very close to those we previously reported for argon and krypton.