Physical Review A

Density behavior of the depolarized-interaction-induced light-scattering line shape in gaseous argon atT=298 K and pressures between 30 and 262 MPa

F. Barocchi, L. Carraresi, Milva Celli

Published Oct 1, 1992• 3 citations

Abstract

We have experimentally investigated the density behavior of the depolarized-interaction-induced light-scattering line shape of compressed gaseous argon at T=298 K and up to pressure p=262 MPa, i.e., to densities n=19.7 atoms/${\mathrm{nm}}^{3}$. We have been able to measure the spectral behavior down to the frequency \ensuremath{\nu}\ensuremath{\approxeq}15 GHz. These low-frequency measurements have permitted the study in detail of the effect of the intensity cancellation which, in the line shape, manifests itself by means of a strong density-dependent rounding of the spectra below \ensuremath{\approxeq}900 GHz.

DOI: 10.1103/physreva.46.r3598

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Physical Review A

Density behavior of the depolarized-interaction-induced light-scattering line shape in gaseous argon atT=298 K and pressures between 30 and 262 MPa

F. Barocchi, L. Carraresi, Milva Celli

Published Oct 1, 1992• 3 citations

Publisher

Abstract

{\mathrm{nm}}^{3}

. We have been able to measure the spectral behavior down to the frequency \ensuremath{\nu}\ensuremath{\approxeq}15 GHz. These low-frequency measurements have permitted the study in detail of the effect of the intensity cancellation which, in the line shape, manifests itself by means of a strong density-dependent rounding of the spectra below \ensuremath{\approxeq}900 GHz.

DOI: 10.1103/physreva.46.r3598

Related papers

Isotropic collision-induced scattering from high-temperature gaseous mercury

Marco Sampoli, F. Hensel, F. Barocchi

We have measured the isotropic collision-induced light-scattering spectrum of a metal vapor, i.e., mercury vapor at temperature T=973 K and densities around 0.113 atom/ ${\mathrm{nm}}^{3}$ , by means of an apparatus which allows us to perform comparisons between polarized and depolarized Raman spectra in high-temperature high-pressure gases and metal vapors. We have then derived an empirical model for the collision-induced polarizability trace of mercury diatom. Similarly to the anisotropy, the obtained trace behaves rather differently from the noble-gas counterpart, showing strong contributions from the electron correlations in the overlap region. \textcopyright{} 1996 The American Physical Society.We have measured the isotropic collision-induced light-scattering spectrum of a metal vapor, i.e., mercury vapor at temperature T=973 K and densities around 0.113 atom/${\mathrm{nm}}^{3}$, by means of an apparatus which allows us to perform comparisons between polarized and depolarized Raman spectra in high-temperature high-pressure gases and metal vapors. We have then derived an empirical model for the collision-induced polarizability trace of mercury diatom. Similarly to the anisotropy, the obtained trace behaves rather differently from the noble-gas counterpart, showing strong contributions from the electron correlations in the overlap region. \textcopyright{} 1996 The American Physical Society.

Physical Review AJun 1, 199612 citations

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John L. Carlsten, A. Szöke, Michael G. Raymer

This paper reports on our studies of near-resonant scattering of laser light in a collisional environment. A pulsed dye laser with a peak power of 55 MW/ ${\mathrm{cm}}^{2}$ was tuned near the 460.73-nm resonance line of strontium and the side emission was observed from an oven containing both strontium vapor and argon buffer gas. The emission was composed of three spectral components: Rayleigh scattering at the frequency of the laser ${\ensuremath{\omega}}_{L}$, fluorescence at the resonance frequency ${\ensuremath{\omega}}_{0}$ of strontium, and a third component at $2{\ensuremath{\omega}}_{L}\ensuremath{-}{\ensuremath{\omega}}_{0}$. These three components have been studied as a function of the frequency and intensity of the laser and also as a function of the argon buffer gas pressure. While the Rayleigh emission was found to vary as ${\ensuremath{\Delta}}^{\ensuremath{-}2}$ ($\ensuremath{\Delta}={\ensuremath{\omega}}_{0}\ensuremath{-}{\ensuremath{\omega}}_{L}$), the fluorescence component, which was produced by Sr-Ar collisions, was found to be asymmetric with the sign of $\ensuremath{\Delta}$ as predicted by line-broadening theory. By measuring the ratio of the intensities of the fluorescence and Rayleigh components, we were able to measure directly the collisional redistribution function, important in the study of radiative transfer in stellar and planetary atmospheres. At high laser intensities all three components were found to saturate. The results were compared with the theoretical predictions of Mollow's steady-state theory. Theoretical fits for the high-intensity results were obtained when the collisional cross sections were taken to be considerably smaller than in our low-intensity measurements. We believe the discrepancy lies in the use of a steady-state theory for a transient experiment. Effects of radiative trapping and spatial averaging are also discussed.This paper reports on our studies of near-resonant scattering of laser light in a collisional environment. A pulsed dye laser with a peak power of 55 MW/${\mathrm{cm}}^{2}$ was tuned near the 460.73-nm resonance line of strontium and the side emission was observed from an oven containing both strontium vapor and argon buffer gas. The emission was composed of three spectral components: Rayleigh scattering at the frequency of the laser ${\ensuremath{\omega}}_{L}$, fluorescence at the resonance frequency ${\ensuremath{\omega}}_{0}$ of strontium, and a third component at $2{\ensuremath{\omega}}_{L}\ensuremath{-}{\ensuremath{\omega}}_{0}$. These three components have been studied as a function of the frequency and intensity of the laser and also as a function of the argon buffer gas pressure. While the Rayleigh emission was found to vary as ${\ensuremath{\Delta}}^{\ensuremath{-}2}$ ($\ensuremath{\Delta}={\ensuremath{\omega}}_{0}\ensuremath{-}{\ensuremath{\omega}}_{L}$), the fluorescence component, which was produced by Sr-Ar collisions, was found to be asymmetric with the sign of $\ensuremath{\Delta}$ as predicted by line-broadening theory. By measuring the ratio of the intensities of the fluorescence and Rayleigh components, we were able to measure directly the collisional redistribution function, important in the study of radiative transfer in stellar and planetary atmospheres. At high laser intensities all three components were found to saturate. The results were compared with the theoretical predictions of Mollow's steady-state theory. Theoretical fits for the high-intensity results were obtained when the collisional cross sections were taken to be considerably smaller than in our low-intensity measurements. We believe the discrepancy lies in the use of a steady-state theory for a transient experiment. Effects of radiative trapping and spatial averaging are also discussed.

Physical Review AMar 1, 1977233 citations

{\mathrm{nm}}^{3}

We have measured the isotropic collision-induced light-scattering spectrum of a metal vapor, i.e., mercury vapor at temperature T=973 K and densities around 0.113 atom/

{\mathrm{nm}}^{3}

, by means of an apparatus which allows us to perform comparisons between polarized and depolarized Raman spectra in high-temperature high-pressure gases and metal vapors. We have then derived an empirical model for the collision-induced polarizability trace of mercury diatom. Similarly to the anisotropy, the obtained trace behaves rather differently from the noble-gas counterpart, showing strong contributions from the electron correlations in the overlap region. \textcopyright{} 1996 The American Physical Society.

The fluorescent spectrum of the Na

D

lines, pressure broadened by Xe and Kr, has been measured for noble-gas densities of 2\ifmmode\times\else\texttimes\fi{}

{10}^{19}

-3\ifmmode\times\else\texttimes\fi{}

{10}^{20}

${\mathrm{cm}}^{\ensuremath{-}3}$; at the lower density, the lines are isolated while, at the higher, they are severely blended. The spectra are obtained in normalized intensity units allowing the nonbinary behavior of the line wing intensity to be clearly observed. At the lower density the broadening is well characterized by isolated binary interactions; at the higher density multiple-perturber interactions dominate. Nonlinearities in the pressure dependence of shifts, widths, and satellite shape are reported.

^{1}

{\mathit{S}}_{0}

${\mathrm{\ensuremath{-}}}^{3}$

{\mathit{P}}_{1}

transition in atomic ytterbium vapor with the use of frequency-modulation spectroscopy. The experimental findings are in good quantitative agreement with theoretical predictions.

^{1}\mathrm{S}_{0}

${\mathrm{\ensuremath{-}}}^{3}$

{\mathrm{P}}_{1}

transition in atomic ytterbium vapor by the use of a frequency-modulated test field propagating collinearly with the scattering field. The experimental results clearly confirm theoretical predictions and demonstrate the significance of the phenomenon for high-resolution laser spectroscopy.

This paper reports on our studies of near-resonant scattering of laser light in a collisional environment. A pulsed dye laser with a peak power of 55 MW/

{\mathrm{cm}}^{2}

was tuned near the 460.73-nm resonance line of strontium and the side emission was observed from an oven containing both strontium vapor and argon buffer gas. The emission was composed of three spectral components: Rayleigh scattering at the frequency of the laser ${\ensuremath{\omega}}_{L}$, fluorescence at the resonance frequency ${\ensuremath{\omega}}_{0}$ of strontium, and a third component at $2{\ensuremath{\omega}}_{L}\ensuremath{-}{\ensuremath{\omega}}_{0}$. These three components have been studied as a function of the frequency and intensity of the laser and also as a function of the argon buffer gas pressure. While the Rayleigh emission was found to vary as ${\ensuremath{\Delta}}^{\ensuremath{-}2}$ ($\ensuremath{\Delta}={\ensuremath{\omega}}_{0}\ensuremath{-}{\ensuremath{\omega}}_{L}$), the fluorescence component, which was produced by Sr-Ar collisions, was found to be asymmetric with the sign of $\ensuremath{\Delta}$ as predicted by line-broadening theory. By measuring the ratio of the intensities of the fluorescence and Rayleigh components, we were able to measure directly the collisional redistribution function, important in the study of radiative transfer in stellar and planetary atmospheres. At high laser intensities all three components were found to saturate. The results were compared with the theoretical predictions of Mollow's steady-state theory. Theoretical fits for the high-intensity results were obtained when the collisional cross sections were taken to be considerably smaller than in our low-intensity measurements. We believe the discrepancy lies in the use of a steady-state theory for a transient experiment. Effects of radiative trapping and spatial averaging are also discussed.