DEPOLARIZED RAYLEIGH SCATTERING IN GASES
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Date
1970
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Publisher
Ohio State University
Abstract
The depolarized Rayleigh spectra have been measured for several substances. a)For the gases $CO_{2}$, OCS and $CS_{2}$ the pressure dependence of the linewidth of the depolarized Rayleigh line has been measured and was found to be linear in the pressure range below 5 atm. From the broadening coefficient a cross-section for reorientation of the angular momentum has been calculated. It appears that the presence of the electric dipole moment of OCS does not play an important role in molecular reorientation. b) Measurements of the depolarized Rayleigh spectrum in $O_{2}$ at pressures up to 10 atm. show weak satellite lines, about 60 GHz displaced to either side of the ordinary Rayleigh line. The presence of these lines is due to the unpaired electronic spin in $O_{2}$. The pressure broadening coefficient for the central peak has been used to calculate a cross-section for reorientation which is compared with a similar cross-section from the Senftleben-Beenakker effect. For the satellites the kinetic theory predicts an initial narrowing with increasing pressure, closely analogous to the Dicke-narrowing of the Doppler width. The experiments indicate that such a narrowing exists. The broadening of the satellites at higher pressures leads to a cross-section, larger than the reorientation cross-section mentioned above. c) It has been verified that the spectrum of light, scattered from a gas of paramagnetic molecules ($O_{2}$), placed in a magnetic field shows a line splitting. This splitting is due to transitions within the Zeeman multiplet and lines are observed displaced by $\pm \omega_{L}$ as well as $\pm 2\omega_{L}$($\omega_{L}$ being the Larmor frequency), in accordance with the selection rules $\Delta m\pm 1, \pm 2$.
Description
Author Institution: Kamerlingh Onnes Laboratory, University of Leiden