Two-photon induced exciton mediated dissociation of N2O and photomobility of O atoms in crystalline Xe

Two-photon induced access of Xe excitons at 248 nm leads to efficient dissociation of N2O impurities via ionic potentials. The product O atoms are probed via the Xe+O− charge transfer transitions, and the N2O disappearance is probed by infrared (IR) spectroscopy. Charge transfer excitation of O atoms leads to atomic mobility, such that with extensive irradiation a photochemical steady-state is reached between N2O, oxygen atoms trapped in the Xe bulk, and within the same cage as N2. A detailed kinetic analysis of these processes is presented. Among the extracted parameters are the two-photon absorption cross section of Xe at 248 nm, 3.7×10−48 cm4 s, the free exciton migration length, 47 Å, and the excitonic dissociation probability of N2O, 0.85. The mobility of photoexcited O atoms is attributed to the topology of electronically excited surfaces which show minima at the ground state cage barriers.