An empirical approximation to the Voigt profile

Whiting, E. E.

doi:10.1016/0022-4073(68)90081-2

Cited by 505 publications

(168 citation statements)

References 4 publications

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“…But this integral function is expensive to compute, particularly when a large number of rotational lines need to be calculated for each iteration step in the inversion calculation. We used an approximate formula for Voigt function derived by Whiting [1968] …”

Section: Discussionmentioning

confidence: 99%

Interactions between impact‐induced vapor clouds and the ambient atmosphere: 1. Spectroscopic observations using diatomic molecular emission

Sugita

Schultz

2003

J. Geophys. Res.

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[1] The importance of interactions between impact-induced vapor clouds and an ambient atmosphere has been widely recognized, and theoretical approaches have provided significant insights. Few experiments, however, have been done to observe directly the energy partitioning during the interactions between impact vapor clouds and the ambient atmosphere. The present study attempts to understand the difference between actual and theoretical model impact vapor clouds produced under an atmosphere. A series of hypervelocity impact experiments was conducted using a spectroscopic measurement method. Plastic (polycarbonate) impactors allowed simulating vaporization phenomena associated with natural impactors (e.g., silicates and metals) at high impact velocities into water. Water as the target material served to suppress the effect of fine-grained fragments from the target. Emission spectra of the leading part of downrange-moving impact vapor clouds were captured with high-speed spectrometers as a function of time for various ambient pressures. The emission spectra exhibit strong molecular bands from carbon compounds as well as blackbody continuum radiation. In order to estimate the temperature of the radiation source, we carried out a spectral-form inversion analysis based on diatomic emission theory. Obtained molecular radiation temperatures range from 4500 K to 5500 K with relatively high accuracy ($2%) and place a number of well-defined constraints for the radiation source. A simple theoretical model that is often assumed for an impact-induced vapor cloud, however, does not readily satisfy the constraints. This strongly suggests that real impact-induced vapor clouds may be more complex than previously thought.INDEX TERMS: 5420 Planetology: Solid Surface Planets: Impact phenomena (includes cratering); 5407 Planetology: Solid Surface Planets: Atmospheres-evolution; 5455 Planetology: Solid Surface Planets: Origin and evolution; 5494 Planetology: Solid Surface Planets: Instruments and techniques; 6022 Planetology: Comets and Small Bodies: Impact phenomena; KEYWORDS: Impact cratering, impact experiments, impact vaporization, impact flash spectroscopy, molecular emission Citation: Sugita, S., and P. H. Schultz, Interactions between impact-induced vapor clouds and the ambient atmosphere: 1.

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Section: Discussionmentioning

confidence: 99%

Interactions between impact‐induced vapor clouds and the ambient atmosphere: 1. Spectroscopic observations using diatomic molecular emission

Sugita

Schultz

2003

J. Geophys. Res.

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“…For all temperatures, the phonon spectra were fit with Voigt profiles, employing the Whiting approximation to determine the width 42,43 . Phonon spectra were corrected for the Bose thermal population factors.…”

Section: Methodsmentioning

confidence: 99%

Phonon softening near the structural transition in BaFe2As2observed by inelastic x-ray scattering

et al. 2011

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In this work we present the results of an inelastic x-ray scattering experiment detailing the behavior of the transverse acoustic [110] phonon in BaFe2As2 as a function of temperature. When cooling through the structural transition temperature, the transverse acoustic phonon energy is reduced from the value at room temperature, reaching a maximum shift near inelastic momentum transfer q = 0.1. This softening of the lattice results in a change of the symmetry from tetragonal to orthorhombic at the same temperature as the transition to long-range antiferromagnetic order. While the lattice distortion is minor, the anisotropy in the magnetic exchange constants in pnictide parent compounds is large. We suggest mechanisms of electron-phonon coupling to describe the interaction between the lattice softening and onset of magnetic ordering.

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“…In this work it is treated by means of the numerical approximation given by Whiting [41]. The natural width ∆λ nat of a line is given by the life times of its upper and lower states.…”

Section: Line Profile Functionmentioning

confidence: 99%

Net emission coefficients of argon iron plasmas with electron Stark widths scaled to experiments

Wendt¹

2011

J. Phys. D: Appl. Phys.

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The net emission coefficient of plasmas containing argon and iron at atmospheric pressure is calculated and analysed for the case of cylindrical geometry. Its values are obtained by integrating the monochromatic net emission coefficient taking into account continuous and line radiation. The width of the spectral lines is determined by Doppler broadening, natural, resonance, van der Waals, electron and ion Stark broadening. As Stark broadening is the most important broadening mechanism in the considered pressure and temperature range, the electron Stark widths are calculated following the semi-empirical Stark broadening theory. Additionally, the electron Stark widths of Ar, Ar+, Fe and Fe+ are multiplied by scaling factors in order to reproduce experimental electron Stark widths. The scaling factor is determined for each species separately. For small plasma radii the net emission coefficient determined here shows good agreement with literature values where spherical geometry is considered while they decrease faster with increasing plasma radius. This behaviour is caused by the increase of the irradiation of the symmetry axis when cylindrical instead of spherical geometry is considered. For radii and temperatures typical of the metal filled core of arcs occurring in gas metal arc welding processes, i.e. radii between 1 and 2 × 10−3 m and temperatures between 5000 and 10 000 K, the scaling of the Stark widths increases the net emission coefficient of iron plasmas by between 2% and 23%. In this parameter range the net emission coefficient of iron plasmas for cylindrical geometry is between 30% and 37% smaller than values calculated for spherical geometry.

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An empirical approximation to the Voigt profile

Cited by 505 publications

References 4 publications

Interactions between impact‐induced vapor clouds and the ambient atmosphere: 1. Spectroscopic observations using diatomic molecular emission

Interactions between impact‐induced vapor clouds and the ambient atmosphere: 1. Spectroscopic observations using diatomic molecular emission

Phonon softening near the structural transition in BaFe2As2observed by inelastic x-ray scattering

Net emission coefficients of argon iron plasmas with electron Stark widths scaled to experiments

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