Osnabrück 2002 – scientific programme

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MO: Molekülphysik

MO 19: Poster II (Energietransfer, Reaktionen, Photoionisation, Femtosekundenspektroskopie, ultrakurze Pulse)

MO 19.11: Poster

Thursday, March 7, 2002, 17:30–19:30, Schloss

Molecular dissociation of metal carbonyls by mid IR femtosecond pulses — •Lars Windhorn, Lars Windhorn, Thomas Witte, Jake Yeston, Detlev Proch, Marcus Motzkus, Karl-Ludwig Kompa, Werner Fuss, Thom as Witte, Jake Yeston, Detlev Proch, Marcus Motzkus, and Karl-Ludwig Kompa — Max-Planck-Institut fuer Quantenoptik, D-85748 Garching, Germany

By focusing an MIR femtosecond laser in a small glass cell containing gas-phase metal carbonyls, the resonant infrared multiphoton dissociation of molecules with femtosecond laser pulses was observed. Cr(CO)6, Mo(CO)6, W(CO)6, and Fe(CO)5 could easily be dissociated, which requires an excitation to at least v = 7 or 8 of the CO stretch vibration. After irradiation with  150 fs pulses at 5000 nm the metal carbonyl practically disappears in favor of free CO, as detected by the IR spectrum. The dissociation probability is independent of repetition rate and a steep function of the radiation energy density. No dissociation is observed with wavelengths out of resonance. By comparing the power dependence of the total conversion with a model, we can infer that only few vibrational degrees of freedom are involved in the excitation process.