VARIATION OF THE RAMAN SPECTRUM OF SOLID HYDROGEN WITH ORTHO–PARA RATIO

Abstract

The frequencies and shapes of the vibrational Raman lines, Q1(0) and Q1(1), of solid hydrogen at 2.1 °K have been studied for a series of ortho–para ratios, co/cp. In the concentration range 0.75 > co > 0.20 and 1.0 > cp > 0.25, each Q line has a single maximum, and can be interpreted in terms of traveling vibrational excitations. For co < 0.20 the Q1(1) line splits into a band of closely spaced lines; at these low concentrations traveling ortho excitations apparently cannot be sustained, and the components of the Q1(1) line represent various nearest-neighbor couplings of ortho molecules. Some observations on the S1(0) line were also made.