Computation of Pressure Effects of Inert-Gas Mixtures on Atomic Line Shapes

1972 ◽  
Vol 5 (2) ◽  
pp. 989-991 ◽  
Author(s):  
Harry C. Jacobson
Keyword(s):  
Gas Mixtures ◽  
Pressure Effects ◽  
Inert Gas ◽  
Atomic Line ◽  
Line Shapes

scholarly journals Pressure effects on water vapour lines: beyond the Voigt profile

2012 ◽  
Vol 370 (1968) ◽  
pp. 2495-2508 ◽  
Author(s):  
N. H. Ngo ◽  
H. Tran ◽  
R. R. Gamache ◽  
J. M. Hartmann
Keyword(s):  
Water Vapour ◽  
Line Shape ◽  
Pressure Effects ◽  
Shape Model ◽  
Line Shapes ◽  
Voigt Profile ◽  
Voigt Model ◽  
Velocity Changes ◽  
Dynamics Simulations ◽  
Induced Velocity

A short overview of recent results on the effects of pressure (collisions) regarding the shape of isolated infrared lines of water vapour is presented. The first part of this study considers the basic collisional quantities, which are the pressure-broadening and -shifting coefficients, central parameters of the Lorentzian (and Voigt) profile and thus of any sophisticated line-shape model. Through comparisons of measured values with semi-classical calculations, the influences of the molecular states (both rotational and vibrational) involved and of the temperature are analysed. This shows the relatively unusual behaviour of H 2 O broadening, with evidence of a significant vibrational dependence and the fact that the broadening coefficient (in cm −1 atm −1 ) of some lines increases with temperature. In the second part of this study, line shapes beyond the Voigt model are considered, thus now taking ‘velocity effects’ into account. These include both the influence of collisionally induced velocity changes that lead to the so-called Dicke narrowing and the influence of the dependence of collisional parameters on the speed of the radiating molecule. Experimental evidence of deviations from the Voigt shape is presented and analysed. The interest of classical molecular dynamics simulations, to model velocity changes, together with semi-classical calculations of the speed-dependent collisional parameters for line-shape predictions from ‘first principles’, are discussed.

Collision-Induced Absorption in Alkali-Metal-Atom—Inert-Gas Mixtures

1973 ◽  
Vol 7 (5) ◽  
pp. 1606-1609 ◽  
Author(s):  
C. Bottcher ◽  
A. Dalgarno ◽  
E. L. Wright
Keyword(s):  
Alkali Metal ◽  
Metal Atom ◽  
Alkali Metal Atom ◽  
Gas Mixtures ◽  
Inert Gas ◽  
Induced Absorption

Atomic line shapes in stellar spectra

2008 ◽  
Author(s):  
John F. Kielkopf ◽  
Nicole F. Allard ◽  
Marco Antonio Gigosos ◽  
Manuel Ángel González
Keyword(s):  
Atomic Line ◽  
Stellar Spectra ◽  
Line Shapes

Conductivity of a photoplasma of sodium vapor-inert gas mixtures

1999 ◽  
Vol 27 (1) ◽  
pp. 182-192 ◽  
Author(s):  
N.A. Gorbunov ◽  
A.S. Melnikov ◽  
I.A. Movtchan ◽  
I. Smurov ◽  
G. Flamant
Keyword(s):  
Gas Mixtures ◽  
Inert Gas ◽  
Sodium Vapor

scholarly journals Recommended isolated-line profile for representing high-resolution spectroscopic transitions (IUPAC Technical Report)

2014 ◽  
Vol 86 (12) ◽  
pp. 1931-1943 ◽  
Author(s):  
Jonathan Tennyson ◽  
Peter F. Bernath ◽  
Alain Campargue ◽  
Attila G. Császár ◽  
Ludovic Daumont ◽  
...  
Keyword(s):  
High Resolution ◽  
Line Profile ◽  
Pressure Effects ◽  
Task Group ◽  
High Resolution Spectroscopy ◽  
Line Shapes ◽  
Neutral Gas ◽  
Voigt Profile ◽  
Simplifying Assumptions ◽  
On Line

Abstract The report of an IUPAC Task Group, formed in 2011 on “Intensities and line shapes in high-resolution spectra of water isotopologues from experiment and theory” (Project No. 2011-022-2-100), on line profiles of isolated high-resolution rotational-vibrational transitions perturbed by neutral gas-phase molecules is presented. The well-documented inadequacies of the Voigt profile (VP), used almost universally by databases and radiative-transfer codes, to represent pressure effects and Doppler broadening in isolated vibrational-rotational and pure rotational transitions of the water molecule have resulted in the development of a variety of alternative line-profile models. These models capture more of the physics of the influence of pressure on line shapes but, in general, at the price of greater complexity. The Task Group recommends that the partially Correlated quadratic-Speed-Dependent Hard-Collision profile (pCqSD-HCP) should be adopted as the appropriate model for high-resolution spectroscopy. For simplicity this should be called the Hartmann–Tran profile (HTP). The HTP is sophisticated enough to capture the various collisional contributions to the isolated line shape, can be computed in a straightforward and rapid manner, and reduces to simpler profiles, including the Voigt profile, under certain simplifying assumptions.

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