Raman scattering tensor elements for some a g modes of anthracene

The intensities of the Raman lines of anthracene in solution and in the pure crystal at room temperature have been measured using several excitation frequencies (ν 0 ) in the pre‐resonance region. The data were used to derive molecular scattering elements α ii at each ν o for a number of a g fundamentals. While the values of α xx and α yy are constant over the restricted range of excitation used, α zz shows an enhancement as ν o moves towards resonance with the first absorption system (I). Overlap factors were determined from the fluorescence spectrum of anthracene in a biphenyl matrix, and these values were used to calculate the contribution α zz (I) due to scattering off the first excited electronic state. Working beyond the oriented‐gas assumption improved the fit between calculated and observed enhancement. There is a measurable background contribution to α zz due to scattering off higher excited states and this has an opposite algebraic sign from α zz (I) for all a g fundamentals except possibly for the 394 cm −1 mode.