Xenon 147-nm resonancefvalue and trapped decay rates

Abstract

The absorption oscillator strength of the xenon 147-nm resonance transition is measured to be 0.264+0.016. This value is from direct absorption measurements with equivalent widths from =1 to =10 cm. This f-value measurement is compared to others in the literature and is used in Monte Carlo simulations of trapped decay rates. The simulations include an angle-dependent partial frequency redistribution. The simulation results are compared to trapped decay rates in the literature.

Photonic superdiffusive motion in resonance line radiation trapping Partial frequency redistribution effects

“…For high opacity samples, the CFR assumption in core radiation is a severe approximation since CFR implies that radiation well into the wings can be emitted in a single scattering event, which can not occur (an upper limit exists) due to the breakdown of the Doppler asymptotic. This contributes to show that the JW-type approximations are only acceptable for small Voigt parameters and for overall center-of-line opacities roughly smaller than 100 − 500 [16,24,31]. The asymptotic analysis of resonance radiation trapping started probably with Holstein seminal work [18] and received afterwards a relevant contribution from van Trigt's infinite opacity expansion analysis in the 1970s [32].…”

“…For strong resonance lines with short lifetimes the frequency redistribution is partial since only a few collisions occur before emission, and consequently the stochastic nature of the distribution must be considered. Partial Frequency Redistribution (PFR) effects are important in an astrophysical context, as is the case of the scattering of Lyα radiation in optically thick nebulae [20] and the Ca I resonance line in the solar spectrum [21], as well as in lab scale atomic vapors, notably the 185 nm mercury line in low-pressure lighting discharges (which can account for as many as 10% of the overall flux in a typical T12 fluorescence lamp) [22] and the 147 and 129 nm Xe VUV radiation used in Plasma Display Pannels (PDPs) applications [23,24]. For both mercury and xenon, the natural lifetimes of the corresponding excited states are less than about 3 ns and therefore only at very high densities is the collision rate high enough to approach CFR conditions.…”

Effective Radiative Lifetimes

“…In Anderson et al [6] also calculated the decay of the resonance radiation in a cylindrical plasma by means of a Monte-Carlo simulation with the assumption of homogeneously distributed resonance atoms and of a partial redistribution of the frequency. They used for their simulation a new value of the oscillator strength for the resonance transition (f-value), estimated by new precise absorption measurements and could eliminate the discrepancy b e tween the measured decay rates of Vermeersch and the results of their own MC-simulation.…”

Trapping of radiation in plasmas

“…(16). Truncating this series at the leading term leads to the "local" approximation for the transport equation:…”

“…28 is the oscillator strength of the 147nm Xe transition. 16 The total pressure broadening is just: which can be substituted directly into Eq. ( 11) to evaluate the line center extinction kp.…”