The effect of neutral nonresonant collisions on atomic spectral lines

Allard, N. F.; Kielkopf, John F.

doi:10.1103/revmodphys.54.1103

Cited by 519 publications

(340 citation statements)

References 329 publications

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“…As was indicated by Mead and Truhlar [10], the calculation of the wave function [11][12][13][14]. On the other hand, they showed that the Born-Huang version [15][16][17] of the adiabatic approximation gives rise to a natural manifestation of geometric phases.…”

Section: Appearance Of Berry Vector Potentials In Pressure-broadened mentioning

confidence: 99%

Does non-cyclic Berry phase play any role in the formation of pressure-broadened spectral line shapes?

Ciuryło

Szudy

Baylis

2017

J. Phys.: Conf. Ser.

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Section: Appearance Of Berry Vector Potentials In Pressure-broadened mentioning

confidence: 99%

Does non-cyclic Berry phase play any role in the formation of pressure-broadened spectral line shapes?

Ciuryło

Szudy

Baylis

2017

J. Phys.: Conf. Ser.

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“…As done in most semi-classical collisional approaches, the approximation of the rectilinear trajectories is adopted in the collisional method of this work. This approximation was validated by several works (see, for example, Smith et al, 1969;Allard & Kielkopf 1982). Furthermore, we assume that the impact approximation is valid where we consider only the binary collisions which are well separated and uncorrelated.…”

Section: Introductionmentioning

confidence: 99%

Scattering Polarisation of the d-States of Ions and Solar Magnetic Field: Effects of Isotropic Collisions

Derouich

Basurah

Badruddin

2017

Publ. Astron. Soc. Aust.

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Analysis of solar magnetic fields using observations as well as theoretical interpretations of the scattering polarization is commonly designated as a high priority area of the solar research. The interpretation of the observed polarization raises a serious theoretical challenge to the researchers involved in this field. In fact, realistic interpretations need detailed investigations of the depolarizing role of isotropic collisions with neutral hydrogen.The goal of this paper is to determine new relationships which allow the calculation of any collisional rates of the d-levels of ions by simply determining the value of n * and Ep without the need of determining the interaction potentials and treating the dynamics of collisions. The determination of n * and Ep is easy and based on atomic data usually available online. Accurate collisional rates allow a reliable diagnostics of solar magnetic fields.In this work we applied our collisional FORTRAN code to a large number of cases involving complex and simple ions. After that, the results are utilized and injected in a genetic programming code developed with C-langugae in order to infer original relationships which will be of great help to solar applications. We discussed the accurarcy of our collisional rates in the cases of polarized complex atoms and atoms with hyperfine structure. The relationships are expressed on the tensorial basis and we explain how to include their contributions in the master equation giving the variation of the density matrix elements.As a test, we compared the results obtained through the general relationships provided in this work with the results obtained directly by running our code of collisions. These comparisons show a percentage of error of about 10% in the average value. Our results could be implemented easily in numerical codes concerned with the simulations of the scattering polarization to obtain accurately the magnetic field in the quiet Sun.

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“…In quasistatic line-broadening theory [1,32], the spectrum of the absorption (fluorescence) line is given by the Fourier transform of the atomic dipole's autocorrelation function (s). When the absorber (emitter) interacts simultaneously with N perturbers, the autocorrelation function is given by…”

Section: Quasistatic Broadening Calculationsmentioning

confidence: 99%

“…Two limiting cases for describing the effect of collisions on line parameters (shift and width) are well known: (1) perturbation due to binary or many-body atomic collisions in the gas phase (reviewed in [1]), and (2) description in terms of the so-called atomic-bubble model which applies to metal atoms embedded in superfluid and solid helium cryomatrices (reviewed in [2]). In the gas phase, the motion of rare-gas atoms is totally uncorrelated even at elevated densities and their interactions with alkali-metal atoms can be treated as independent processes.…”

Section: Introductionmentioning

confidence: 99%

“…When the density of atoms is so high that the absorber or emitter at any moment interacts with a large number of perturbers, the motion of the perturbers becomes unimportant and the broadening results from fluctuations of the number of perturbers located in the interaction volume that can be described by a Poissonian distribution. In that case, the line shape approaches a Gaussian profile with a spectral width γ that is proportional to √ ρ 0 and a shift that is a linear function of ρ 0 [1,3].…”

Section: Introductionmentioning

confidence: 99%

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Spectroscopy of alkali-metal atoms in dense supercritical4He at low temperatures

2013

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We present an experimental study of laser-induced fluorescence spectra of Cs atoms embedded in superfluid and solid 4 He, as well as in dense supercritical fluid He. The studied temperature range is increased with respect to earlier studies by the use of intense laser pulses for the transient local heating of the helium sample. The analysis of the experimental spectra is based on two different approaches: the atomic-bubble model and quasistatic line-broadening theory in the limit of high perturber density. Our results indicate that the temperature dependence of the experimentally observed spectra can be traced back to temperature-dependent correlations in the motion of He atoms in the sample.

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The effect of neutral nonresonant collisions on atomic spectral lines

Cited by 519 publications

References 329 publications

Does non-cyclic Berry phase play any role in the formation of pressure-broadened spectral line shapes?

Does non-cyclic Berry phase play any role in the formation of pressure-broadened spectral line shapes?

Scattering Polarisation of the d-States of Ions and Solar Magnetic Field: Effects of Isotropic Collisions

Spectroscopy of alkali-metal atoms in dense supercritical4He at low temperatures

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