Line shapes in resonance fluorescence for external sources near unit optical depth

1988 ◽  
Vol 66 (1) ◽  
pp. 93-99
Author(s):  
W. S. C. Brooks ◽  
D. J. W. Kendall ◽  
E. J. Llewellyn ◽  
I. C. McDade
Keyword(s):  
Optical Depth ◽  
Line Shape ◽  
Atomic Oxygen ◽  
Local Environment ◽  
Resonant Scattering ◽  
Kinetic Temperature ◽  
Resonance Fluorescence ◽  
Beam Source ◽  
Line Shapes ◽  
External Sources

The angle-dependent resonant scattering line shape is calculated for a two-state atomic gas with a kinetic temperature similar to that of an external beam source for optical depths of less than or equal to unity. It is demonstrated that narrowing of the backscattered line shape occurs for all source temperature to absorber temperature ratios. It is also shown that there is no appreciable broadening when the source and absorption temperatures are different. The small amount of broadening that does occur is due to an enhancement of scattered radiation at frequencies away from the resonance-line centre frequency.Rocket-based resonance lamp measurements of atomic oxygen concentrations are complicated by the height-dependent optical depth for the 130.2, 130.4, and 130.6 nm oxygen emissions as well as by the nodification of the local environment and relative positions of the emission and absorption line shapes due to the motion of the rocket vehicle through the atmosphere.

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.

Critical Raman line shape behavior of fluid nitrogen

2004 ◽  
Vol 76 (1) ◽  
pp. 147-155 ◽  
Author(s):  
M. Musso ◽  
F. Matthai ◽  
D. Keutel ◽  
K.-L. Oehme
Keyword(s):  
Raman Line ◽  
Line Shape ◽  
Line Broadening ◽  
Vibrational Resonance ◽  
Critical Isochore ◽  
Molecular Fluids ◽  
Detection Techniques ◽  
Gas Phases ◽  
Line Shapes ◽  
Band Position

Isotropic Raman line shapes of simple molecular fluids exhibit critical line broadening near their respective liquid-gas critical points. In order to observe this phenomenon, it is essential that the band position of a given vibrational mode is density-dependent, and that vibrational depopulation processes negligibly contribute to line broadening. Special attention was given to the fact that the isotropic (i.e., nonrotationally broadened) line shape of liquid N2 is affected by resonant intermolecular vibrational interactions between identical oscillators. By means of the well-chosen isotopic mixture (14N2).975 - (14N15N).025, the temperature and density dependences of shift, width, and asymmetry of the resonantly coupled 14N2 and, depending on the S/N ratio available, of the resonantly uncoupled 14N15N were determined, with up to milli-Kelvin resolution, in the coexisting liquid and gas phases and along the critical isochore, using a highest-resolution double monochromator and modern charge-coupled device detection techniques. Clear evidence was found that vibrational resonance couplings are present in all dense phases studied.

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.

13C NMR-spektroskopische Untersuchungen an Äthylaluminiumverbindungen / 13C NMR Spectroscopic Investigations of Ethylaluminium Compounds

1976 ◽  
Vol 31 (6) ◽  
pp. 730-736 ◽  
Author(s):  
R. Rottler ◽  
C. G. Kreiter ◽  
G. Fink
Keyword(s):  
Temperature Dependence ◽  
Exchange Reaction ◽  
13C Nmr ◽  
Line Shape ◽  
Nmr Spectra ◽  
Exchange Process ◽  
Kcal Mole ◽  
Line Shapes ◽  
Calculated Line ◽  
C Nmr

The 13C NMR spectra of the ethylaluminium compounds [Al(C2H5)xCl3_x]2 x = 1, 1,5, 2 and 3 are presented and factors governing the temperature dependence of the line shape are discussed. The exchange reaction of terminal ethyl groups for chlorine ligands and ethyl ligands, resp., in ethylaluminium-sesquichloride was investigated by fitting the calculated line shapes to the observed spectra.The energy of activation of this exchange process was determined as to be 12,3 ‡ 1,5 kcal/mole. The synthesis of 13C2-[Al(C2H5)Cl2]2 is described.

A computational insight into the relationship between side chain IR line shapes and local environment in fibril-like structures

2021 ◽  
Vol 154 (8) ◽  
pp. 084105
Author(s):  
Sandra M. V. Pinto ◽  
Nicola Tasinato ◽  
Vincenzo Barone ◽  
Laura Zanetti-Polzi ◽  
Isabella Daidone
Keyword(s):  
Local Environment ◽  
Side Chain ◽  
Line Shapes ◽  
The Relationship ◽  
Insight Into

Development of a supersonic O(3PJ), O(1D2) atomic oxygen nozzle beam source

1980 ◽  
Vol 51 (2) ◽  
pp. 167-182 ◽  
Author(s):  
Steven J. Sibener ◽  
Richard J. Buss ◽  
Cheuk Yiu Ng ◽  
Yuan T. Lee
Keyword(s):  
Atomic Oxygen ◽  
Beam Source ◽  
Nozzle Beam

THE SHAPES OF PHOTOELECTRON SATELLITE SPECTRA

2002 ◽  
Vol 09 (02) ◽  
pp. 1209-1212 ◽  
Author(s):  
V. G. YARZHEMSKY ◽  
V. I. NEFEDOV ◽  
M. YA. AMUSIA ◽  
L. V. CHERNYSHEVA
Keyword(s):  
Line Shape ◽  
Shape Parameters ◽  
Line Shapes ◽  
Peak Structure ◽  
Experimental Line

Line shapes of photoionization satellites are theoretically investigated. Calculations were carried out for the satellite states 1s2s(3S)3s(2S) and 3s3p5(1P)4s(2P) of Ne 1s and Ar 3p vacancies, respectively, created in photoionization. Theory excellently reproduces experimental line shape parameters of the first satellite and predicts the two-peak structure of the second.

Monte-Carlo simulation of single-line resonance scattering in a rarefied gas

1991 ◽  
Vol 69 (8-9) ◽  
pp. 1146-1153 ◽  
Author(s):  
I. D. Lockerbie ◽  
W. S. C. Brooks ◽  
P. How ◽  
E. J. Llewellyn
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Multiple Scattering ◽  
Rarefied Gas ◽  
Resonant Scattering ◽  
Resonance Scattering ◽  
Single Line ◽  
Gas Temperature ◽  
Line Shapes ◽  
Simulation Results

A Monte-Carlo simulation of single-line resonant scattering in a rarefied gas is presented and the technique is applied to the interpretation of a rocket-borne resonance-lamp experiment. The simulation examines the case of an emitting and absorbing gas at the same temperature for a number of detector and source configurations. The distance from the last scatter point, the angular distribution of the detected scattered photons, and the line shape formed by the scattered photons, at the detector, are evaluated for these different configurations. The simulation results suggest that the scattering of the detected photon occurs very near to the rocket, and not necessarily in the traditional scattering region at the intersection of the detector and emitter normals. It is observed that multiple scattering plays an important role in the number of photons detected and that the apparent gas temperature, as exhibited by the line shapes of the scattered photons, is dependent upon the configuration of the experiment. The simulation results suggest that, for a resonance-scattering experiment to measure constituent concentrations, the experimental design must optimize the return signal and minimize the effect of multiple scattering. The results also suggest that the calibration procedures for resonance-scattering experiments must be made with a physical configuration and environment that is identical to that expected in the rocket flight.

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