Brillouin Spectra of Liquids Using He–Ne Laser*

Brillouin spectra of six liquids (acetone, ethyl alcohol, water, carbon bisulfide, toluene, and carbon tetrachloride) have been obtained using a He–Ne laser as the light source and employing photoelectric detection. The velocity of sound has been measured with a precision of ±0.2% in most cases. The intensities of the central component and the Brillouin components have been measured. Since the liquid samples were prepared so that they were sensibly optically empty, a comparison of the intensities can be made with the theoretical predictions of Landau and Placzek.