Berlin 2001 – wissenschaftliches Programm
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MO: Molekülphysik
MO 12: Posters Friday: Spectroscopy
MO 12.7: Poster
Freitag, 6. April 2001, 12:30–15:00, AT3
Spectroscopy and Photodissociation of ClF in rare gas solids — •Matias Bargheer, Jörg Pietzner, Peter Dietrich, and Nikolaus Schwentner — Institute of Experimental Physics, FU-Berlin, Arnimallee 14, 14195 Berlin
ClF molecules (chlorine monofluoride) isolated in rare gas matrices provide the perspective to study both experimentally and theoretically important aspects of molecular dynamics and chemistry in the condensed phase, such as cage exit, mobility and recombination. As a diatomic molecule in an ordered environment the system is simple enough to allow for detailed modeling. On the other hand it is relatively easy to prepare and electronic transitions are accessible by UV femtosecond lasers so that time-resolved measurements of the dynamical processes are possible.
Vibrational progressions in the A′ → X fluorescence in the spectral range from 600 to 900 nm with 141 ms lifetime are reported. Two-photon excitation leads to emission from the ionic D′ state in the range from 390 to 470 nm with 50 ns life time. Spectroscopically, ground state parameters ω e and ω exe as well as Te values for the A′ and D′ states are derived. Matrix shifts and Stokes shifts are observed and the large line width of the D′ emission is related to the strong coupling of the ionic state to the lattice.
The A′ → X fluorescence allows to monitor the ClF content in bleaching experiments: Dissociation quantum efficiencies of 5% and 4.8% are determined for kinetic energies of the F fragment of 0.92 eV and 0.39 eV in Ar (19 K), respectively. In contrast to the F2 molecule, the dissociation efficiency for ClF decreases at lower temperatures (5K), indicating delayed cage exit.