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The relative XeF(B-X) emission spectra from the steady-state vacuum ultraviolet photolysis of XeF2 in presence of the bath gas (He, Ar, Kr, Xe) have been used to study the energy relaxation of XeF(B,C) molecules. The measurements were carried out at two photolysis wavelengths (160 and 135 nm) for analysis of different ranges of vibrational levels. XeF*(B) vibrational and rotational distributions were assigned for various bath gas pressures. Significant rotational heating resulting from collision induced energy exchange was registered. Numerical modeling of XeF(B) vibrational populations and the intensity ratio as a function of pressure leads to the model for state-to-state processes. Vibrational relaxation within electronic state can be described by one-quantum transitions. For He as the bath gas, electronic state transfer is characterized by an exponential gap low. The large loss of vibrational energy per collision in Ar, Kr, and Xe is satisfactorily described by electronic state-changing collisions. The rotational temperatures observed in emission spectra correspond to average vibrational energy, which is lost in collision induced electronic transitions. Modeling of XeF* energy relaxation in Xe showed that there is a dependence of quenching efficiency on the vibrational level number.
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