Speed-Dependent Effects on the 748.8 nm Ne Self-Broadened Line

Abstract

Profiles of the self-broadened 748.8 nm Ne line emitted from a glow discharge in neon in the pressure range between 0.8 and 100 Tr were measured using an improved experimental setup with pressure-scanned Fabry-Perot interferometer. First, line profiles were analysed using an ordinary Voigt procedure which yielded the Doppler widths decreasing with the increase in neon pressure. Using a speed-dependent Voigt profile it was shown that for the 748.8 nm line the correlation between the Doppler and collisional broadening plays an important role. However, the values of the pressure broadening and shift coefficients determined by the speed-dependent Voigt analysis were found to be only slightly different from those obtained by the ordinary Voigt analysis. A systematic error in the determination of perturber concentration in onr previous investigation was corrected.

Temperature Effects on Dissociative Recombination in Neon

“…It is thus shown that in the case of lower perturbing gas pressures the observed line profile is affected by an excitation process that could be the dissociative recombination of molecular ions Ne + 2 with electrons. This result agrees very well with our earlier studies [2,7,10,13,14] of the 748.8 nm Ne line, where we showed (see Fig. 6 in [10]) that the population fraction of non--thermalized atoms decreases with the neon pressure, and their role in the formation of the total line profile (3) is negligible for neon pressures higher than 8 Torr.…”

“…D0 is the dissociation energy of the Ne + 2 molecular ion (in eV). Data in last row are taken from our earlier papers [7,10]. For experimental data the values of standard uncertainties are given.…”

“…7. Plots of the mean dissociative width γDIS against the mean Doppler temperatures TD (experimental points: full circles -this paper, triangle - [7,10]). Error bars indicate the value of the standard uncertainty.…”

“…8. Plots of the energy of crossing of potential curves Ecr against the mean Doppler temperatures TD (experimental points: full circles -this paper, triangle - [7,10]). D0 is the dissociation energy of the molecular ion Ne neon line in the course of the earlier studies [7,10] using different discharge lamp of an earlier construction [17].…”

“…These departures were satisfactorily explained [2] as caused by the dissociative recombination of molecular ions Ne + 2 with electrons. Frommhold and Biondi [3] suggested, however, that also in the case of argon the process of dissociative recombination of molecular Ar In recent years a systematic study of the shapes of the 687.1 nm, 703.0 nm and 750.3 nm self-broadened argon lines as well as 540.0 nm and 748.8 nm neon lines emitted from low-current glow discharge sources has been performed in our laboratory using a pressure--scanned Fabry-Perot interferometer (FPI) [4][5][6][7][8]. For the 687.1 nm and 703.0 nm Ar lines and the 748.8 nm Ne line we have found that at pressures below 3 Torr the observed profiles differ markedly from the Voigt function.…”