J. Szudy

Effect of dissociative recombination on spectral line profiles in neon glow discharge

In the present study we have shown that the dissociative recombination of Ne2+ ions which gives rise to non-thermalized Ne atoms may be regarded as the main process responsible for the distortion of the profiles of the 753.5 and 754.4 nm neon lines. The distorted profiles were analysed as a superposition of the Ballik profile for thermalized atoms and the modified Ballik profile for non-thermalized atoms and the Lorentzian and Gaussian widths as well as the relative density of non-thermalized and thermalized atoms have been determined. We have found for the dissociation energy of the neon molecular ion Ne2+ in the 2 Sigma u+ state the value D=(1.20+or-0.08) eV. We have also found for the 3d6 excited neon atoms of speed 1275 m s-1 the excitation transfer cross section Q3d6 with a value Q3d6=(39+or-15)*10-16 cm2.

On the role of Dicke narrowing in the formation of atomic line shapes in the optical domain

The purpose of this work is to verify the possibility of the observation of the Dicke narrowing of atomic spectral lines in the optical domain. As an example we have chosen experimental results obtained by means of a laser-induced fluorescence method for the 114Cd 326.1 nm line perturbed by xenon. Experimental results were carefully reanalysed using a line shape model which takes into account the speed dependence of collisional broadening and shifting, the velocity-changing collisions and the collision-time asymmetry. We have found no convincing evidence for the occurrence of Dicke narrowing of the 326.1 cadmium line perturbed by xenon. The Dicke narrowing (if it occurs at all) appears to be smaller than that resulting from the estimation based on the accessible data describing the diffusion of Cd in Xe. As a source of this behaviour the correlation between velocity-changing and dephasing collisions was indicated.

Non-adiabatic approach to the asymmetry of pressure broadened spectral lines

Abstract A semi-classical formula for the asymmetry of the profile of pressure broadened spectral lines, which takes into account non-adiabatic processes is derived. The resultant spectrum is shown to be given as a linear combination of the Lorentzian and dispersion profiles. The line profile asymmetry can be evaluated in cases when the degeneracy of both the initial and final states is important.

Low-pressure broadening and shift of 3p54s-3p5np (n=4, 5, 6) argon spectral lines perturbed by He, Ne, Ar

Low-pressure broadening and shift of three spectral lines of argon: 667.7 nm (3p54s-3p54p), 430.0 nm (3p54s-3p55p) and 360.6 nm (3p54s-3p56p), emitted from a low current glow discharge in pure argon, Ar-Ne and Ar-He mixtures have been investigated by means of a Fabry-Perot interferometer. The values of the pressure broadening and shift coefficients are determined.

Response of scanning Fabry-Perot interferometers to asymmetric spectral line profiles

A detailed discussion of the effect of adding the dispersion-shaped component to the Lorentzian profile on the resulting line profile recorded by an ideal scanning Fabry-Perot interferometer is presented. An analytic correction to the Ballik formula for the response of a Fabry-Perot interferometer is derived which makes it possible to determine quantitatively the magnitude of the collision-time asymmetry in the line profiles.

Asymmetric line broadening

Using a laser-induced fluorescence method a detailed analysis of the profiles of the 114Cd326.1 nm line perturbed by all rare gases was performed which revealed departures from the ordinary Voigt profile. These departures are shown to be consistent with fits of experimental profiles to a speed-dependent asymmetric Voigt profile or asymmetric Voigt profile.