Knowledge Bank

Much of our knowledge of solid $H2$ has emerged from an investigation of its Raman and induced infrared $spectra1$. Study of the induced spectrum of $H2$ in the condensed state, which began in the late 50s, is still being pursued in various laboratories as a front line area. The very recent work of Patel and $co-workers2-4$ devoted to the study of the spectrum in the regions of the first, second and third overtones has uncovered a wealth of information. A particularly interesting result is the evaluation of the transverse-optical and longitudinal-optical phonon densities in p $H2$ from its infrared spectrum. The present paper aims at giving an upto date review of the spectroscopic work on condensed hydrogen.