Hannover 2010 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 7: Poster: Femtosecond Spectroscopy
MO 7.16: Poster
Dienstag, 9. März 2010, 16:00–18:30, Lichthof
CRASY: Correlated Rotational Alignment Spectroscopy Resolves Fragmentation Channels — •Christian Schröter, Kyriaki Kosma, Ingolf-Volker Hertel, and Thomas Schultz — Max-Born-Institut, Max-Born-Str. 2A, 12489 Berlin
Mass spectroscopy yields information on the composition of molecules and clusters. When the formed compounds are weakly bound they may break apart which leads to an increased ion yield in the fragment. Here we address the question how to distinguish between fragmented and unfragmented signals.
We developed a CRASY method which combines the techniques of rotational alignment with femtosecond-pump-probe spectroscopy in a two pulse experiment. An IR pulse generates a coherent rotational wave packet by means of nonadiabatic alignment. After a variable delay, we probe the wave packet by a UV pulse which excites and ionizes the molecule via a resonant electronic state. Every ion signal is modulated with a rotational frequency linked to the ground state geometry, since the transition dipole moments are fixed in the rotating molecular frame. This mass-CRASY method yields mass-rotational spectra.
We demonstrate the technique using CS2 as a model system with distinct fragmentation channels and discuss fragmentation paths for selected rotational states.