Molecular Scattering of Ruby-Laser Light

Abstract

The advent of the laser has made it possible to conduct a more complete study of Rayleigh scattering. In the present experiment the angular distribution of light scattered by gas molecules was measured from 45 to 135° from the direction of the incident beam in argon and xenon. The experiment was conducted both in the plane of polarization of the incident laser beam and in the plane perpendicular to it. Absolute values of the differential-scattering cross section are determined for neon, argon, xenon, oxygen, nitrogen, air, carbon dioxide, sulphur hexafluoride, and propane at NTP. The experimental results obtained with noble gases are compared with Rayleigh's theory. It is found that the ruby-laser light beam is not scattered isotropically either by argon or by xenon as predicted by the linear theory, in the plane perpendicular to the plane of polarization. In the plane of polarization the scattered intensity appears to be consistent with a cosinesquared distribution. The measured differential-scattering cross sections for noble gases at 60° are found to be approximately twice as large as the theoretical values.

Light Scattering

“…An attempt to explain this observation theoretically failed (303). However, by utilizing the slightly modified experimental arrangement of George et al (116), Watson and Clark (327) could not detect any noticeable change in the angular pattern for nitrogen predicted by the theory for either polarization of the incident beam. Stray light is probably the cause of large variations in the values of the depolarization ratio of different gases and vapors reported recently by several authors (36, 80, 218, 327), although these new values are considerably lower than the older results.…”

“…Gases. A departure from the Rayleigh scattering was reported for the angular distribution of scattered intensity of argon and xenon at atmospheric or lower pressures with the incident radiation vertically polarized (116). An attempt to explain this observation theoretically failed (303).…”

“…Lasers are utilized as light sources in several other instruments for measurements on gases (26,116,327) and solids (12,93,94,228,229,275). Other instruments for measurements on gases are the one (218) for the visible part of the spectrum and the other (119) for the vacuum ultraviolet.…”

A study of electric dipole radiation via scattering of polarized laser light

“…9 The only study that we have found that deals with the angular distribution of scattered polarized light is by George et al, who studied the scattering of polarized light from gas atoms. 10 This work, however, contains a large discrepancy between theory and experiment which the authors did not explain.…”

The CI calculation of the frequency-dependent polarizability and some optical properties for N2and O2

“…It is known that the absolute measurement of Rayleigh scattering intensity is difficult [18], and the data for a few molecular gases are found in literature at a limited wavelength [18][19][20][21]. If the molecule is randomly oriented, the total scattering cross section a(v) is given [22,23] by…”