Profiles of Pressure Broadened Spectral Lines in an Arc Plasma

Spectral analysis of the alkali metals is characterized by pressure profiles. In the present work an electric arc has been used to calibrate the half-width of the intensity used in the construction of the ArI natural line at 4300 Å with a trace of evaporated rubidium at pressures of 1, 2 and 3 atmospheres. The results agree well with those obtained by Kusch’s line absorption equation in an electric furnace in the point of view of impact approximation, showing that the widths of the lines have Lorentz shapes. It is found that a simple treatment can be given using the quasi-static approximation of pressure broadening developed by Unsöld. The agreement of the results is good only if the shifts are large. The study shows that the pressure line profile is made up of a sum of dispersion profiles and asymmetric terms which arise from interactions of quadratic Stark effect, commonly assumed to be the force in causing foreign gas broadening

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Die Druckverbreiterung der diffusen Heliumlinien, Vergleich zwischen Messung und Theorie im quasistatischen Bereich

Zeitschrift für Naturforschung A ◽

10.1515/zna-1966-0605 ◽

1966 ◽

Vol 21 (6) ◽

pp. 697-718 ◽

Cited By ~ 13

Author(s):

H. Pfennig ◽

E. Trefftz

Keyword(s):

Stark Effect ◽

Point Of View ◽

Spectral Lines ◽

Experimental Point ◽

Line Profiles ◽

Experimental Conditions ◽

Part D ◽

Upper Level ◽

Good Agreement ◽

Red Wing

It is difficult to discriminate between theories of pressure broadening of spectral lines through comparison with experiments. Line profiles are insensitive with respect to details of the theory, and it is difficult to keep experimental conditions clear and certain enough to make the comparison relevant. We used measurements of VIDAL 1 which are satisfactory from the experimental point of view. The wings of the diffuse He-lines 2P — nD are compared with those calculated by quasistatic theory. Part B deals with STARK effect splitting of the upper level. Part C describes the quasistatic theory of the line wings, and discusses the probability function of the so called micro field strength. In part D the results of the calculation are compared with the measurements. The comparison is relevant only for the violet wings of the triplet series. The red wing of the triplet lines and the violet wing of the singlet lines are disturbed by the forbidden component 2P — nP. The red wing of singlet lines is experimentally too inexact because of disturbing wings of neighboring triplet lines. The slope of the violet side of the triplet wings shows good agreement between theory and measurement for the far wing (large Δv). For decreasing Δv the experimental curve stays below the theoretical curve. For comparison of wing intensities it proves to be important to normalize the line profiles. It is seen that the measured height of the wings increases less with increasing main quantum number than the theoretical height.

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Pressure Broadening of UV Lines

Highlights of Astronomy ◽

10.1017/s1539299600000599 ◽

1971 ◽

Vol 2 ◽

pp. 561-565

Author(s):

H. van Regemorter

Keyword(s):

Electron Density ◽

Neutral Hydrogen ◽

Uv Spectra ◽

Line Broadening ◽

Pressure Broadening ◽

Static Approximation ◽

Impact Approximation ◽

Typical Time ◽

Static Regime ◽

The Impact

Most of the lines in the UV spectra are lines of ions which are formed in high temperature regions where the pressure broadening is caused by electrons and protons. This is the case in O and B type stars for which the theoretical calculation of the width of all the strong UV lines is important in determining both the blanketing effect and the abundances of the elements.The cores of these strong lines are formed in non-LTE layers near the surface where the electron density is very low. The wings of some of the lines are more easy to interpret, being formed in deeper layers of the star, where one can assume LTE and where the electron density - or in the Sun, the neutral hydrogen density - is such that the pressure broadening is much more important than the natural width.Two opposite approximations have been applied to the line broadening problem; the impact approximation is generally valid for electrons when the perturbations are so rapid that the collision timeτcis very small compared to the typical time, Δω-1, of importance in computing the profile at the frequencyΔω = ω – ω0measured from the line centre. On the contrary, whenτc≫Δω−1the quasi static approximation may be assumed. Both of these approximations have been considerably improved and efforts have been made recently to develop a unified theory valid from the impact regime to the static regime.

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Pressure Broadening of Some He I Lines

International Journal of Spectroscopy ◽

10.1155/2010/983578 ◽

2010 ◽

Vol 2010 ◽

pp. 1-7 ◽

Cited By ~ 3

Author(s):

Banaz Omar

Keyword(s):

Stark Effect ◽

Statistical Approach ◽

Stark Broadening ◽

Line Broadening ◽

Pressure Broadening ◽

Dense Plasmas ◽

Quasistatic Approximation ◽

Line Shapes ◽

Quadratic Stark Effect ◽

Quantum Statistical

Quantum statistical approach is adopted for calculating the spectral line shapes of neutral helium in dense plasmas. Stark broadening of isolated He I lines 5048 Å (), 3889 Å (), and 3188Å () is presented. Based on thermodynamic Green's function, the electronic contribution to the shift and width is considered. The participation of ions to the line broadening is treated in a quasistatic approximation, by taking both quadratic Stark effect and quadrupole interaction into account. The calculated shifts and widths are compared with existing data.

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From the Vector to Scalar Perturbations Addition in the Stark Broadening Theory of Spectral Lines

Universe ◽

10.3390/universe7060176 ◽

2021 ◽

Vol 7 (6) ◽

pp. 176

Author(s):

Valery Astapenko ◽

Andrei Letunov ◽

Valery Lisitsa

Keyword(s):

Spectral Line ◽

Stark Effect ◽

Coulomb Field ◽

Spectral Lines ◽

Alternative Methods ◽

Scalar Perturbation ◽

Numerical Comparison ◽

Line Shapes ◽

Stark Effects ◽

The Impact

The effect of plasma Coulomb microfied dynamics on spectral line shapes is under consideration. The analytical solution of the problem is unachievable with famous Chandrasekhar–Von-Neumann results up to the present time. The alternative methods are connected with modeling of a real ion Coulomb field dynamics by approximate models. One of the most accurate theories of ions dynamics effect on line shapes in plasmas is the Frequency Fluctuation Model (FFM) tested by the comparison with plasma microfield numerical simulations. The goal of the present paper is to make a detailed comparison of the FFM results with analytical ones for the linear and quadratic Stark effects in different limiting cases. The main problem is connected with perturbation additions laws known to be vector for small particle velocities (static line shapes) and scalar for large velocities (the impact limit). The general solutions for line shapes known in the frame of scalar perturbation additions are used to test the FFM procedure. The difference between “scalar” and “vector” models is demonstrated both for linear and quadratic Stark effects. It is shown that correct transition from static to impact limits for linear Stark-effect needs in account of the dependence of electric field jumping frequency in FFM on the field strengths. However, the constant jumping frequency is quite satisfactory for description of the quadratic Stark-effect. The detailed numerical comparison for spectral line shapes in the frame of both scalar and vector perturbation additions with and without jumping frequency field dependence for the linear and quadratic Stark effects is presented.

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Color Hues in Fluorescent Proteins with the Same Chromophore are due to Internal Quadratic Stark Effect

Biophysical Journal ◽

10.1016/j.bpj.2009.12.2229 ◽

2010 ◽

Vol 98 (3) ◽

pp. 413a ◽

Cited By ~ 1

Author(s):

Mikhail Drobizhev ◽

Shane Tillo ◽

Nikolay S. Makarov ◽

Aleksander Rebane ◽

Thomas Hughes

Keyword(s):

Stark Effect ◽

Fluorescent Proteins ◽

Quadratic Stark Effect

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Asymmetry in Solar Spectral Lines

Highlights of Astronomy ◽

10.1017/s1539299600001891 ◽

1974 ◽

Vol 3 ◽

pp. 171-203 ◽

Cited By ~ 5

Author(s):

C. Magnan ◽

J. C. Pecker

Keyword(s):

Velocity Field ◽

Numerical Experiment ◽

Point Of View ◽

Spectral Lines ◽

Single Line ◽

The Asymmetry

AbstractAfter reviewing observations of the spectral solar features originated either in the chromospheric layers or in the photospheric layers, from the point of view of the observations, and after having shown the strikingly discrepant set of interpretations that can be found currently in literature, a numerical experiment is performed in a case not too different from the solar case. It is shown that the use of the line bisector to determine, from the asymmetry of a single line, the trend of the velocity field might be considerably misleading, a fact which explains partly the results published in literature.

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Atomic Physics of the 12-μm and Related Lines

Symposium - International Astronomical Union ◽

10.1017/s0074180900124568 ◽

1994 ◽

Vol 154 ◽

pp. 297-307

Author(s):

Edward S. Chang

Keyword(s):

Atomic Physics ◽

Stark Effect ◽

Disk Center ◽

Emission Peak ◽

Emission Lines ◽

Line Profiles ◽

Great Progress ◽

Quadratic Stark Effect ◽

Rydberg Transitions ◽

Made In

The 12 μm emission lines were unexpectedly detected about a decade ago. Great progress has been made in understanding the atomic physics underlying these high-l Rydberg transitions in Mg I and other atoms. In a magnetic field, their Landé g factor is shown to be unity. At disk center, the shift of the absorption trough relative to the emission peak is demonstrated to be due to the quadratic Stark Effect, permitting measurement of the photospheric electric field strengths. Other related lines of Mg I require accurate atomic fine structure data to interpret properly their complex line profiles. Related lines are found in the ATMOS spectra for C I, Na I, Al I, Si I, Ca I, and Fe I, in addition to H I.

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