RAYLEIGH-BRILLOUIN LIGHT-SCATTERING STUDY OF SATURATED NORMAL-BUTANE BETWEEN ROOM-TEMPERATURE AND THE CRITICAL-POINT

In the present investigation, photon correlation spectroscopy in an extended form has been used for studying both the Rayleigh and Brillouin components of a dense fluid including their intensity ratio (Landau-Placzek ratio). As for the Brillouin component this amounts to spectroscopy in the ultrasonic region. Results for both phases of saturated n-butane in a broad temperature range are reported. They are compared with data from various sources. Although the approach to the critical temperature was limited (1.5 K for the liquid, 0.95 K for the vapour) the transition from normal to critical behaviour is distinctly marked.