Absorption Spectra of Three Catacondensed Hydrocarbons in Compressed Plastic Media

The electronic spectra of the catacondensed hydrocarbons phenanthrene, 1,2-benzanthracene, and chrysene in the plastic media lucite, polystyrene, cellulose acetate, and polyvinyl acetate reveal a red shift with increasing pressure. The magnitude of the spectral displacement ranges from 200–900 cm−1 at 27 kbar for the various electronic transitions. The red shift may be interpreted by the Bayliss model for solvent shifts and the assumption that the solute cavity radius varies inversely with the pressure. An unusual pressure dependence of the La band shape of 1,2-benzanthracene is observed and may arise from overlapping electronic transitions.