Dresden 2011 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 24: Poster: Femtosecond spectroscopy

MO 24.14: Poster

Donnerstag, 17. März 2011, 16:00–18:00, P2

CRASY: Correlated Rotational Alignment Spectroscopy Yields Structure Selective Spectroscopic Data — •Christian Schröter, 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, but it gives no information about molecular structure or fragmentation occurring in the ionization process. Electron spectroscopy yields information on the electronic structure, but usually with an insufficient resolution to assign molecular structure. To derive structure selective information out of ion masses and emitted electrons, we coupled the mentioned methods to high resolution rotational Raman spectroscopy.

We employ the 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 non-adiabatic alignment. After a variable delay, we probe the wave packet by a UV pulse which excites and ionizes molecules and molecular clusters via a resonant electronic state. Every ion and electron 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. Therefore the CRASY method yields mass-rotational spectra and electron-rotational spectra with unprecedented information content.

We present results obtained with this technique for carbon-disulfide monomer and dimer and the molecule butadiene and its clusters.