Temperature dependence of the width of the Raman Q branch in liquids nitrogen and oxygen

Abstract

Interferometric measurements have been made of the width of the Q branch in the Raman spectra of saturated liquids N2 and O2 over the complete range from the respective triple points (63.15 K,54.35 K) to within 1 K of the critical point (126.26 K,154.58 K) in each case. The temperature dependence is similar for both liquids in the region above the normal boiling points (77.36 K,90.19 K): Near the latter temperatures the widths are 2 to 3 GHz, and the dominating feature is a sharp increase in width (to about 20 GHz) as the critical points are approached. A similar but less pronounced increase was also observed near the triple point in liquid O2. In the case of liquid N2, however, the linewidth remained approximately constant in the region below the normal boiling point.