NEW MEASUREMENT OF THE TRACE OF THE HELIUM DIATOM POLARIZABILITY FROM THE COLLISION-INDUCED, POLARIZED, RAMAN-SPECTRUM

Collision-induced Raman spectra of helium at 30 amagats are obtained, with incident beam polarization parallel and perpendicular to the direction of observation. The comparison reveals the presence of a polarized continuum not seen before in any gas. A wave-mechanical computation of this polarized spectrum, utilizing as input an ab initio calculation of the trace of the helium diatom polarizability, agrees with the observation. Thus a second, independent measurement of the isotropic part of the diatom polarizability is obtained. © 1979 The American Physical Society.