Set-up combining synchrotron radiation-induced photochemistry with IR probing:: (HCl)n in Kr matrix

An FTIR spectrometer samples with an optimized beam guiding optics the volume irradiated with VUV radiation from a high flux beamline and monitors photochemical reaction products. Additionally UV and visible fluorescence spectra are recorded. Dissociation efficiencies for HCl monomers and multimers in Kr matrix are rather similar. The increase in absorption cross-section with multimer size is compensated by a decreasing dissociation quantum efficiency. The H atom cage exit probability of monomers is only some percent in contrast to previous results, and the discrepancy is attributed to saturation effects in fluorescence spectroscopy of electronic transitions in the Cl products. Build-up and decay of Cl-HCl and H-HCl intermediates are monitored and simulated. (C) 2000 Elsevier Science B.V. All rights reserved.