Bonn 2000 – wissenschaftliches Programm

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MO: Molekülphysik

MO 4: Ultraschnelle Dynamik in Clustern (gemeinsam mit FV Atomphysik)

MO 4.1: Vortrag

Montag, 3. April 2000, 15:15–15:30, HS V

Subpicosecond Photodissociation of MnCp(CO)₃ and Chirp-Dependent Molecular Dynamics in Na₃ — •P. Rosendo-Francisco, S. Minemoto, C. Kaposta, C. Lupulescu, M. Krenz, A. Bartelt, S. Vajda, and L. Wöste — Institut für Exp.-Physik, FU Berlin, Arnimallee 14, D-14195 Berlin

The photodissociation of MnCp(CO)₃ was studied in molecular beams by using intense fs pulses at 800 nm and 400 nm. The effect of the laser pulse energy on the relative fragmentation yield of different fragments was studied. Time resolved mass spectra indicated that the fragmentation process is completed within 2 ps after excitation. This observation was confirmed by pump and probe spectra. Our results are in a good agreement with photofragmentation studies on different metal-ligand systems reported recently by other research groups [1,2]. In the case of the sodium trimer, we employed femtosecond pulses at 620 nm. In the case of using unchirped pulses we observed the symmetric stretch mode of the B-state of the Na₃ [3,4]. Depending on the chirp superimposed on the pump pulse, the pseudorotation mode or evolution of a wavepacket created in the X- state (populated via the B-state by the chirped pump pulse) was observed. The oscillatory signal (T_OSC = 230 fs) reveals vibrational frequencies observed earlier by using unchirped amplified pulses [4]. [1] S. Trushin et al., J. Phys. Chem. A 102 4129 (1998) [2] G. Gerber et al., Science 282 919 (1998) [3] S. Rutz et al., Z. Phys. D 40 25 (1997) [4] T. Baumert et al., Chem. Phys. Lett. 209 29 (1993).