Doppler broadening

About: Doppler broadening is a research topic. Over the lifetime, 5509 publications have been published within this topic receiving 92552 citations.

Collision broadening and shift in the resonance line of calcium

Abstract: The broadening and shift of the calcium resonance line, lambda 4227 angstroms, have been measured with high accuracy when the line is formed in absorption under pressures of He, Ne, Ar, Kr, and Xe up to one atmosphere. He and Ne cause symmetrical broadening over the entire pressure range in agreement with the predictions of the 'impact theory'. The onset of asymmetrical broadening indicating breakdown of the 'impact approximation', is noticed at pressures of Ar, Kr, and Xe close to one atmosphere. The peculiar way in which broadening and shift change with perturbing gas is discussed in terms of 6-12 and 6-8-12 interatomic potentials.

Experimental observation of rotational Doppler broadening in a molecular system.

Abstract: The first experimental evidence of rotational Doppler broadening in photoelectron spectra, reported here, show good agreement with recently described theoretical predictions. The dependence of the broadening on temperature and photoelectron kinetic energy is quantitatively predicted by the theory. The experiments verify that the rotational contributions to the linewidth are comparable to those from translational Doppler broadening and must be considered in the analysis of high-resolution photoelectron spectra. A classical model accounting for this newly observed effect is presented.

Analytical formula for radiation trapping with partial frequency redistribution

Abstract: A highly realistic Monte Carlo code is used to simulate radiation trapping including effects due to partial frequency redistribution and with a spectral line profile dominated by natural (radiative) broadening resonance collisional broadening and Doppler broadening. Results from 294 simulations are used to determine the fundamental mode trapped decay rate in cylindrical geometry over a very wide range of parameter space including a factor of in gas density, a factor of 1000 in column radius, and a factor of 1000 in Doppler width. The fundamental mode decay rates are fitted to an analytical formula expressed in terms of three dimensionless parameters which can conveniently be applied to a variety of gases, column radii and Doppler widths.

Enthalpy Measurement in Inductively Heated Plasma Generator Flow by Laser Absorption Spectroscopy

Abstract: Laser absorption spectroscopy was applied for diagnostics of inductively heated plasma generator flows. Temporal variation of translational temperature was deduced from measured absorption line broadening because the flow properties fluctuated at 300 Hz in synchronization with the induction current. The specific total enthalpy and mole fraction of oxygen were estimated from the deduced temperature assuming thermochemical equilibrium. Consequently, the averaged degree of dissociation of oxygen is 0.92. The specific total enthalpy was estimated at 33.7 ± 2.9 MJ/kg; 39% of it was in the form of chemical potential. The results show good agreement with intrusive measurements.

Density of atoms in Ar*(3p54s) states and gas temperatures in an argon surfatron plasma measured by tunable laser spectroscopy

Abstract: This study presents the absolute argon 1 s (in Paschens’s notation) densities and the gas temperature, Tg, obtained in a surfatron plasma in the pressure range 0.65 10 mbar, for which the pressure broadening can no more be neglected. Tg is in the range of 480-750 K, increasing with pressure and decreasing with the distance from the microwave launcher. Taking into account the line of sight effects of the absorption measurements, a good agreement is found with our previous measurements by Rayleigh scattering of Tg at the tube center. In the studied pressure range, the Ar(4 s) atom densities are in the order of 1016−1018 m−3, inc...