<title>Correlation Spectroscopy</title>

Abstract

Today, the interpretation of spectroscopic data with the aid of time-dependent autocorrelation functions (acfs) has found widespread application to molecules in solids, liquids and dense gases. In this paper the two dominant relaxation processes influencing the acts of rotational and vibrational relaxation are reviewed. The influence of Coriolis coupling on the rotational acfs of degenerate vibrations is emphasized. Experimental acfs are discussed for the rotational relaxation of HC1 in tetrachlorides, OH- and OD- ions in single crystals of alkalihalides, gaseous chloroform and of methanes in liquid argon as well as for intramolecular vibrational relaxation in the metal carbonyls Cr(CO)6, Mo(CO )6 and W(CO)6.