VIBRATION-ASSISTED INTERMOLECULAR HYDROGEN TUNNELING IN PHOTOREACTIVEDOPED MOLECULAR-CRYSTALS - EFFECT OF TEMPERATURE AND PRESSURE

The pressure and temperature dependence of the reaction rate of the ph otochemical intermolecular W-transfer reaction in acridine-doped fluor ene single crystals exhibit all typical features of solid state H-tunn eling. Independent Raman data including the pressure dependence have i dentified three low energy inter-and intramolecular vibrational fluctu ations as reaction promoting modes. The mode identification allows a m ore subtle analysis of the H-transfer reaction rate behavior on the ba sis of recent theoretical concepts. Surprisingly, the complete data se t k(P, T) can be satisfactorily reproduced by an average one frequency mode model with parameters consistent with an average of the paramete rs calculated for the individual reaction promoting modes.