Hannover 2003 – wissenschaftliches Programm
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MO: Molekülphysik
MO 12: Poster II
MO 12.21: Poster
Donnerstag, 27. März 2003, 16:00–18:30, Lichthof
Determination of H2 vibrational line profiles with femtosecond time resolved CARS — •Hrvoje Skenderović, Tiago Buckup, Wendel Wohlleben, and Marcus Motzkus — Max-Planck-Institut für Quantenoptik, D-85748 Garching, Germany
Femtosecond resolved nonresonant CARS (Coherent Anti-Stokes Raman Scattering) is applied to probe hydrogen and hydrogen mixtures with Ar, He and N2 [1]. The experimental transients of the H2 Q-branch ro-vibrational transitions show detailed beating structures, reflecting the ro-vibrational dynamics of the electronic ground state.
Modelling of the experimental data yields J-dependent collisional line-shifts and line-broadening constants even at high pressures, where frequency-domain CARS spectra are difficult to model due to the overlapping of the spectral lines.
The results for pure H2 both for line-shift and line-broadening show excellent agreement with the values obtained by other groups with the high-resolution CARS in frequency domain. The dependence of the experimental broadening coefficients on perturber density in mixtures shows also a good agreement with the literature: a linear dependence in the case of hydrogen and helium as perturbers and explicit nonlinear behavior in the case of nitrogen and argon. The role of inhomogeneous broadening in time domain CARS is discussed.
[1]H. Skenderović, T. Buckup, W. Wohlleben, M. Motzkus, J. Raman Spectrosc. 33, 866 (2002).