scholarly journals The Coulomb Symmetry and a Universal Representation of Rydberg Spectral Line Shapes in Magnetized Plasmas

Symmetry ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1922
Author(s):  
Andrei Letunov ◽  
Valery Lisitsa
Keyword(s):  
Spectral Line ◽  
Line Shape ◽  
Coulomb Field ◽  
Analytical Description ◽  
New Method ◽  
Magnetized Plasmas ◽  
Balmer Series ◽  
Line Shapes ◽  
Symmetry Properties ◽  
Atomic States

A new method of line shape calculations of hydrogen-like atoms in magnetized plasmas is presented. This algorithm makes it possible to solve two fundamental problems in the broadening theory: the analytical description of the radiation transition array between excited atomic states and an account of a thermal ion motion effect on the line shapes formation. The solution to the first problem is based on the semiclassical approach to dipole matrix elements calculations and the usage of the specific symmetry properties of the Coulomb field. The second one is considered in terms of the kinetic treatment of the frequency fluctuation model (FFM). As the result, one has a universal description of line shapes under the action of the dynamic of ion’s microfield. The final line shape is obtained by the convolution of the ionic line shape with the Voigt electron Doppler profile. The method is applicable formally for large values of principal quantum numbers. However, the efficiency of the results is demonstrated even for well known first members of the hydrogen Balmer series Dα and Dβ lines. The comparison of obtained results with accurate quantum calculations is presented. The new method may be of interest for investigations of spectral line shapes of hydrogen-like ions presented in different kinds of hot ionized environments with the presence of a magnetic field, including So L and divertor tokamak plasmas.

scholarly journals The Coulomb Symmetry and a Universal Representation of Rydberg Spectral Line Shapes in magnetized Plasmas

2020 ◽  
Author(s):  
Andrei Letunov ◽  
Lisitsa Valery
Keyword(s):  
Spectral Line ◽  
Line Shape ◽  
Coulomb Field ◽  
Analytical Description ◽  
New Method ◽  
Magnetized Plasmas ◽  
Balmer Series ◽  
Line Shapes ◽  
Motion Effect ◽  
Atomic States

A new method of line shape calculations of hydrogen-like atoms in magnetized plasmas is presented. This algorithm makes it possible to solve two fundamental problems in the broadening theory: the analytical description of the radiation transition array between excited atomic states and account of a thermal ion motion effect on the line shapes formation. The solution to the first problem is based on the semiclassical approach to dipole matrix elements calculations and the usage of the specific symmetry properises of the Coulomb field. The second one is considered in terms of the kinetic treatment of the frequency fluctuation model (FFM). As the result one has a universal description of line shapes under the action of the dynamic of ion’s microfield. The final line shape is obtained by the convolution of the ionic line shape with the Voigt electron-Doppler profile. The method is applicable formally for large values of principle quantum numbers. However, it is demonstrated the efficiency of the results even for well known first members of the hydrogen Balmer series Dalpha and Dbeta. The comparison of obtained results with accurate quantum calculations is presented. The new method may be of interest for investigations of spectral line shapes of hydrogen-like ions presented in different kinds of hot ionized environments with the presence of a magnetic field, including SoL and divertor tokamak plasmas.

scholarly journals Self-Absorption Analysis of Silver Resonance Lines in Nano-Material Laser Produced Plasma

2018 ◽  
Author(s):  
Ashraf M. El Sherbini ◽  
Mohamed A. Hagras ◽  
Mohamed R. Rizk ◽  
El-Sayed A. El Badawy ◽  
Christian G. Parigger
Keyword(s):  
Spectral Line ◽  
Line Shape ◽  
Absorption Analysis ◽  
Shape Distortion ◽  
Laser Device ◽  
Balmer Series ◽  
Line Shapes ◽  
Nano Material ◽  
Temperature And Pressure ◽  
532 Nm

The resonance spectra of neutral silver indicate self-absorption for the studied Ag I lines at the wavelengths of 327.9 nm and 338.2 nm. The center dip is associated with self-reversal due to self-absorption in the plasma. The Q-switched radiation of 355 nm, 532 nm, or 1064 nm from a Nd:YAG laser device generates the plasma at the surface of silver nano-material targets, with experiments conducted in standard ambient temperature and pressure laboratory air. Procedures for recovery of the spectral line shapes confirm that over and above the effects of self-reversal, line shape distortion are important in the analysis. The work discusses parameters describing self-absorption when using fluence levels of 2 to 33 J/cm2 to generate the plasma. Furthermore, subsidiary calibration efforts that utilize the hydrogen alpha line of the Balmer series show that the Ag I lines at 827.35 nm and 768.7 nm are optically thin.

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

Universe ◽  
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.

The impact theory of spectral line shapes: a paradigm shift

2013 ◽  
Vol 91 (11) ◽  
pp. 879-895 ◽  
Author(s):  
A.D. May ◽  
W.-K. Liu ◽  
F.R.W. McCourt ◽  
R. Ciuryło ◽  
J. Sanchez-Fortún Stoker ◽  
...  
Keyword(s):  
Spectral Line ◽  
Line Shape ◽  
Paradigm Shift ◽  
Wigner Distribution ◽  
Kinetic Equations ◽  
Line Profiles ◽  
Line Shapes ◽  
Experimental Line ◽  
Impact Theory ◽  
The Impact

An overview of the binary collision impact theory of spectral line shapes has been given to provide a unified statistical mechanical approach to line-shape theory, laser theory, nonlinear optics, and transport phenomena in dilute gases. The computation of spectral line profiles corresponding to those obtained from ultra-high-resolution spectral line-shape measurements requires numerical ab initio calculation of scattering amplitudes directly from the underlying dynamics of collisions between radiatively active molecules and their perturbers. The Wigner distribution function–density matrix is utilized to describe the kinetic theory of spectral line shapes and to discuss the various collisional processes that contribute to the kernel of kinetic equations. The influence of features of the potential energy surface on spectral parameters is also discussed, and the importance of comparing experimental line profiles directly with numerically computed line shapes obtained from reliable interaction potentials is emphasized. This contrasts sharply with the universal practice of comparing experimental line widths and shifts using some average or approximate theoretical scattering cross-sections and it contrasts sharply with fitting experimental profiles to some convenient analytical line-shape model; hence the phrase “a paradigm shift” in the title of this work.

Collisional Narrowing and the Foreign Gas Broadening of Spectral Line Shapes

1972 ◽  
Vol 50 (22) ◽  
pp. 2792-2800 ◽  
Author(s):  
H. R. Zaidi
Keyword(s):  
Spectral Line ◽  
Line Shape ◽  
Point Of View ◽  
Many Body ◽  
Spectral Line Shape ◽  
Many Body Theory ◽  
Line Shapes ◽  
The Many ◽  
The Impact ◽  
Body Theory

The problem of collisional narrowing and broadening of spectral line shape in a gas is considered from the point of view of propagator technique of the many body theory. The case in which the radiator and perturbers are of different species is considered in this paper. In the impact limit, the propagator equations reduce to a form which is a generalization of the classical equations used in the previous theories. The line shapes resulting from the two approaches are compared and possible generalizations are discussed.

Effects of atomic states interference on spectral line shapes in MMM-Theory

1997 ◽  
Author(s):  
I. N. Kosarev ◽  
C. Stehlé ◽  
N. Feautrier ◽  
A. V. Demura ◽  
V. S. Lisitsa
Keyword(s):  
Spectral Line ◽  
Line Shapes ◽  
Atomic States

New Method for Spectral Line Shape Fitting and Critique on the Voigt Line Shape Model

1995 ◽  
Vol 49 (10) ◽  
pp. 1438-1453 ◽  
Author(s):  
Pekka E. Saarinen ◽  
Jyrki K. Kauppinen ◽  
Jari O. Partanen
Keyword(s):  
Spectral Line ◽  
Line Shape ◽  
Linear Prediction ◽  
Molecular Spectroscopy ◽  
Spectral Lines ◽  
New Method ◽  
Detailed Knowledge ◽  
Spectral Line Shape ◽  
Shape Fitting ◽  
Parametric Line

In this work we introduce a new method for testing spectral line shape models and optimizing the parameters in any parametric model. Given some general parametric line shape and a piece of a spectrum, the method finds the optimal values for the parameters and gives a number which tells how well the spectrum under consideration is explained by that model. The number of spectral lines under analysis may be more than one, and their exact locations need not be known. This characteristic follows from the property that the method does not need the information about line positions and amplitudes at all. Thus, in the absence of a singlet line, a set of overlapping lines can also be analyzed. The analysis is carried out in the signal domain by utilizing linear prediction. Application examples of the method to a molecular spectrum measured in gas phase are given. The results suggest that the Voigt line shape, despite its common use, is not a correct model in molecular spectroscopy. Its limitations become evident when one is trying to enhance the resolution by linear prediction, which requires detailed knowledge of the line shape. Instead a stochastic model, which is also tested, turns out to be rather promising.

scholarly journals The Frequency Fluctuation Model for the van der Waals Broadening

2021 ◽  
Author(s):  
Andrei Letunov ◽  
Valery Lisitsa ◽  
Valery Astapenko
Keyword(s):  
Experimental Data ◽  
Spectral Line ◽  
Line Shape ◽  
Frequency Fluctuation ◽  
Neutral Particles ◽  
Line Shapes ◽  
First Time ◽  
Analytical Expressions ◽  
Fluctuation Model ◽  
Good Agreement

The effect of atomic and molecular microfied dynamics on spectral line shapes is under consideration. This problem is treated in the framework of the Frequency Fluctuation Model (FFM). For the first time the FFM is tested for the broadening of a spectral line by neutral particles. The usage of the FFM allows one to derive simple analytical expressions and perform fast calculations of the intensity profile. The obtained results was compared with Chen and Takeo theory (CT), which is in a good agreement with experimental data. It was demonstrated that for moderate values of temperature and density the FFM successfully describes the effect of the microfield dynamics on a spectral line shape.

H NMR Evidence for a Change in The Local Hydrogen Environment of Sites Associated with the Staebler-Wronski Effect in a-Si:H

2002 ◽  
Vol 715 ◽  
Author(s):  
T. Su ◽  
Robin Plachy ◽  
P. C. Taylor ◽  
S. Stone ◽  
G. Ganguly ◽  
...  
Keyword(s):  
Line Shape ◽  
Defect Density ◽  
Hydrogen Atoms ◽  
Hydrogen Environment ◽  
H Nmr ◽  
Line Shapes ◽  
Different Temperatures ◽  
Staebler Wronski Effect

AbstractWe study the H NMR line shapes of a sample of a-Si:H under several conditions: 1) as grown, 2) light-soaked for 600 hours, and 3) light-soaked followed by annealing at different temperatures. At T = 7 K, the NMR line shape of the sample after light soaking exhibits an additional doublet compared to that of the sample as-grown. This doublet is an indication of a closely separated hydrogen pair. The distance between the two hydrogen atoms is estimated to be about (2.3 ± 0.2) Å. The concentration of these hydrogen sites is estimated to be between 1017 and 1018 cm-3 consistent with ESR measurements of the defect density after light soaking. This doublet disappears after the sample is annealed at 200°C for 4 hours.

Testing the Planet Hypothesis: A Search for Variability in the Spectral‐Line Shapes of 51 Pegasi

1997 ◽  
Vol 478 (1) ◽  
pp. 374-380 ◽  
Author(s):  
Artie P. Hatzes ◽  
William D. Cochran ◽  
Christopher M. Johns‐Krull
Keyword(s):  
Spectral Line ◽  
Line Shapes
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