Parts | Days | Selection | Search | Downloads | Help

MO: Molekülphysik

MO 24: High Resolution Spectroscopy

MO 24.2: Talk

Tuesday, March 14, 2006, 14:15–14:30, H10

The influence of nuclear spin statistics on femtosecond degenerate four wave mixing spectroscopy of polyatomic systems — •Maksim I. Kunitski, Christoph Riehn, Victor V. Matylitsky, and Bernhard Brutschy — Institute of Physical and Theoretical Chemistry, Johann Wolfgang Goethe-University Frankfurt/M., Marie-Curie-Str. 11, D-60439 Frankfurt/M., Germany

Recently, femtosecond time-resolved degenerate four-wave mixing (fs DFWM) has been introduced as a new technique for high-resolution molecular spectroscopy. We have applied this kind of spectroscopy for investigating nitromethane (CH₃NO₂) at room temperature. In the fs DFWM spectrum of CH₃NO₂ new recurrences of A-type with a period of 1/(8A) and an additional intensity modulation were discovered [1]. Also, new recurrences of J-type with a period of 1/[4(B+C)] were assigned by us in the fs DFWM spectra of SO₂ and NO₂, A, B and C being the rotational constants. The incorporation of nuclear spin statistics (NSS) into our fs DFWM simulation model allows us to successfully reproduce all these new features. It will be discussed in detail that the symmetry exclusion of certain rotational levels by NSS can cause a regular pattern in the frequency domain. Consequently, this can lead to new time-domain recurrences. Thus the amount of information obtainable from fs DFWM spectra is increased and the understanding of such spectra significantly improved.

[1] C. Riehn, M. I. Kunitski, V. V. Matylitsky, M. F. Gelin, and B. Brutschy, Phys. Chem. Chem. Phys. 7, 3955 (2005).