Hannover 2016 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 15: Femtosecond Spectroscopy 3
MO 15.3: Vortrag
Donnerstag, 3. März 2016, 11:45–12:00, f102
VUV-induced dissociation of H2O studied by single-shot autocorrelation — •Arne Baumann1, Dimitrios Rompotis1, Oliver Schepp1, Marek Wieland1,2,3, and Markus Drescher1,2,3 — 1Institut für Experimentalphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany — 2The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg, Germany — 3Centre for Free-Electron-Laser Science (CFEL), Luruper Chaussee 149, 22761 Hamburg, Germany
The femtosecond dissociation dynamics of the water molecule upon excitation into the à (1B1) state have been studied by a single-shot autocorrelation pump-probe experiment in the vacuum ultraviolet spectral range. The scheme is based on wave-front splitting of intense Ti:Sa fifth harmonic pulses at 161.8 nm and a colliding pulse geometry, mapping the temporal delay onto a spatial coordinate. This dramatically decreases acquisition time compared to traditional delay-scanning approaches, increasing the statistical precision of the measurement.
Isotope substitution has been utilized to study the primary and secondary kinetic isotope effects on the reaction dynamics of this prototypical over-the-barrier dissociation reaction. Depending on the degree of hydrogen substitution the observed dynamics take place in 10 ± 2 fs and less.