ENVIRONMENTAL-EFFECTS ON THE ENERGETICS AND PHOTOINDUCED DYNAMICS OF MOLECULAR-STATES

Environmental effects on electronic states of small molecules in solid rare gases and in liquids have severe consequences on the photochemis try; examples for valence, Rydberg and ionic states as well as the con nection to photochemical dry etching are treated. The repulsive intera ction of Rydberg states and the solvation of valence and ionic states are related to spectroscopic properties like gas-to-matrix shifts, Sto kes shifts and linewidths. Differential shifts of Rydberg and valence states are illustrated for NO in rare gas matrices and Fano-type line shapes are attributed to a coherent interaction of broad Rydberg multi phonon continua with valence zero phonon lines. For F-2 in Ne a depert urbation of ion-pair and Rydberg states is demonstrated again to origi nate from a differential shift. For Cl-2 the formation of additional s tates due to intermolecular charge transfer from the matrix to the gue st molecules is observed. H2O serves as an example to show that repuls ive surfaces are strongly modified if the character of the state chang es from Rydberg type to valence type with internuclear distance. Infor mation on the dynamics in the femtosecond time scale is derived from i ntensities in overtone progressions of resonance Raman spectra and it is demonstrated that the solvent induces predissociation of the B (3) Pi(0u+) state of I-2 within 300 fs in CCl4, and within 40 fs in liquid Xe.