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MO: Molekülphysik
MO 6: Dissociation and other Collision Processes
MO 6.9: Talk
Tuesday, April 3, 2001, 18:00–18:15, H1058
ClF in rare gas matrices: cage exit and recombination dynamics on fs timescale — •Matias Bargheer, Jörg Pietzner, Peter Dietrich, and Nikolaus Schwentner — Institute of Experimental Physics, FU-Berlin, Arnimallee 14, 14195 Berlin
We establish ClF (chlorine monofluoride) in rare gas matrices as a model system to investigate chemical reactions in the condensed phase on the femtosecond timescale.
Vibrational progressions in the A′ → X fluorescence in the spectral range from 600 to 900 nm are used to monitor the ClF content in bleaching experiments indicating a high recombination rate of about 96%. The emission from the ionic D′ state in the range from 390 to 470 nm after two-photon excitation is used to study the femtosecond dynamics of ClF molecules by pump-probe spectroscopy using LIF as the detection signal. The molecule is excited with UV-femtosecond pulses either into a repulsive singlet 1Π state which is bound by the matrix cage only or into the bound triplet 3Π 0 (B-) state above its gas phase dissociation limit. The excess energy of the F-fragment is varied from 0.4 to 1.1 eV.
Systematic variation of the probe wavelength from 270 to 330 nm yields information on the recombination and relaxation dynamics on timescales from 100 fs to 100 ps. We discuss geminate and nongeminate recombination as well as ultrafast spin-flip (singlet to triplet). The dynamics of the F-fragment after dissociation is monitored by pump-probe spectroscopy of the KrxF complex.