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Düsseldorf 2007 – scientific programme

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MO: Fachverband Molekülphysik

MO 56: Poster: Femtosecond Spectroscopy

MO 56.3: Poster

Thursday, March 22, 2007, 16:30–18:30, Poster A

Collision-induced decay of rotational coherence of N2-molecules — •Philipp Giese, Nina Owschimikow, and Nikolaus Schwentner — FU Berlin, Institut für Experimentalphysik, Arnimallee 14, 14195 Berlin

Interaction of the anisotropy polarizability Δα of a molecule with a short and intense linearily polarized laser pulse induces a transient recurrent alignment of the molecular axis along the field dirction. The revivals of the rotational wave packet are probed via the optically induced Kerr effect. In gases at atmospheric pressure, the rotational coherence persists for several hundred ps. Populations and phases are modified only by bimolecular collisions, which makes gases an ideal model system to study the dynamics of alignment. We non-adiabatically create a rotational wavepacket using IR laser pulses (785 nm) of 150 fs duration with a power density of 1012 W/cm2, and subsequently monitor the collision-induced decay of the rotational revivals in pure N2 as well as mixtures of N2/O2 and N2/Ar at pressures up to 3 atm. The experimental results are compared with models [1] and [2] for the influence of the environment. The investigations are extended to higher densities up to molecular dopants in crystalline matrices.
[1] S.Ramakrishna, T. Seideman J. Chem. Phys. 124, 244503 (2006)
[2] B. Lavorel et al. J. Raman Spectr. 31, 77 (2000)

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