Raman Polarization Study of Quantum and Classical Liquids; ³He, ⁴He, Ne, and Ar

Polarization property of Raman spectra of simple fluids 3He, 4He, Ne, and Ar has been measured. We have clearly found the polarized spectra in the large energy shift region for 3He and 4He. For 4He, we have estimated the s-wave contribution and have found that the ratio of the s-wave to the d-wave increases with an increase of pressure for both super fluid and normal fluid phases. We have also observed the polarized spectra in the large energy shift region for liquid Ne, but the amount of this contribution to the total scattering intensity is small. For liquid Ar, the polarized part is very weak but feasible. The observation of the polarized part suggests that the repulsive interaction due to the electron overlap effect is important in the Raman process of the simple fluids and we also found that the polarized part decreases with a decrease of a quantum nature of these fluids.