An improved line shape model for the matrix ENDOR response in disordered systems

1977 ◽  
Vol 67 (5) ◽  
pp. 1990 ◽  
Author(s):  
P. A. Narayana ◽  
Michael K. Bowman ◽  
David Becker ◽  
Larry Kevan ◽  
Robert N. Schwartz
Keyword(s):  
Line Shape ◽  
Disordered Systems ◽  
Shape Model ◽  
The Matrix

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.

scholarly journals Doppler line shape model for the W I 5d56s—5d56p transition at 400.9 nm in tokamaks

2019 ◽  
Vol 61 (12) ◽  
pp. 125017
Author(s):  
A Sepetys ◽  
R Guirlet ◽  
J Rosato ◽  
Y Marandet
Keyword(s):  
Line Shape ◽  
Shape Model

Characterization of the Electron Density in Si+-Implanted InP by Means of Raman Scattering by Lo-Plasma Coupled Modes

1998 ◽  
Vol 540 ◽  
Author(s):  
J. Ibáñez ◽  
R. Cuscó ◽  
N. Blánco ◽  
G. González-Díaz ◽  
J. Jiménez ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Electron Density ◽  
Line Shape ◽  
Ion Beam ◽  
Coupled Modes ◽  
Shape Model ◽  
Sn Doping ◽  
Average Value ◽  
Ion Beam Implantation

AbstractWe have studied by means of Raman spectroscopy the electron density in two different n-type InP samples with similar doping densities, obtained, respectively, by ion-beam implantation of 150 keV Si+ and by uniform Sn doping during LEC growth. The Raman spectra recorded at 80 K display in both cases the L+ and L– phonon-plasmon coupled modes. For the homogeneously doped InP:Sn sample, a simultaneous fit to the L+ and L– peaks of a line shape model based on the Lindhard-Mermin dielectric function yields accurate values of the charge density. In the implanted sample, the nonuniformity of the charge distribution substantially broadens the L+ modes, but the line shape fit to the L– mode still yields an average value of the electron density in the region probed by the laser beam.

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