Berlin 2005 – wissenschaftliches Programm
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MO: Molekülphysik
MO 24: Theory I
MO 24.7: Vortrag
Samstag, 5. März 2005, 15:30–15:45, HU 2097
Internal dynamics in (CH3)3SnCl: FT-MW and Permutation-Inversion (PI) group theoretical investigations — •Melanie Schnell1,2, Jens-Uwe Grabow1, and Jon Hougen2 — 1Universität Hannover, Institut für Physikalische Chemie, D-30167 Hannover — 2National Institute of Standards and Technology, Optical Technology Division, Gaithersburg, MD 20899, USA
The rotational spectrum of the C3v-symmetric trimethyl tin chloride (CH3)3SnCl, a molecule with three methyl tops connected to a tin atom, has been studied using a pulsed supersonic jet FT microwave spectrometer. The internal rotations of the methyl tops are hindered by barriers of about 150 cm−1 leading to a complex splitting pattern of the rotational levels. Consequently, one single rotational transition of (CH3)3SnCl splits into more than 1000 lines due to internal rotation, quadrupole coupling of the chlorine nucleus, and the large amount of Sn and Cl isotopomers. The high barrier group theoretical tunneling-rotational formalism appropriate for the PI group G162 is used to support the spectroscopic analysis by deriving splitting patterns of the rotational levels as well as statistical weights. A combination of group theory and Stark effect measurements have been used to determine the dipole moment of (CH3)3SnCl to be 4.0925(41) D and to distinguish between levels of the different rotational-torsional species of G162, since only the A1, A2, I4 and I5 levels will have solely a second order Stark effect. It can be shown that the A1 and A2 species in G162 can be fitted to a rigid rotor Hamiltonian enabling the determination of the Sn–Cl bond length to 2.5448 Å.