Abstract book - Prof. Per Jensen, Ph.D. - Bergische Universität ...

Poster session, J42 205High Resolution Spectroscopy and Vibrational Dynamicsof Methane 12 CH 4 and 13 CH 4 up to 12000 cm -1O. N. Ulenikov 1, 2 , E. S. Bekhtereva 1, 2 , S. Albert 1 , S. Bauerecker 1, 3 ,H.-M. Niederer 1 , and M. Quack 11 Physical Chemistry Laboratory, ETH-Zürich, CH-8093, Zürich, Switzerland; 2 TomskState University, Physics Department, 634050, Tomsk, Russia; 3 Technische UniversitätBraunschweig, D - 38106, Braunschweig, GermanyUlenikov O.N.Bekhtereva E.S.Albert S.Bauerecker S.Niederer H.-M.Quack M.The present work is part of a larger study of a systematic analysis of the spectra of methaneisotopomers 1, 2 in relation to the potential hypersurface of methane. 3 We report infraredspectra of 12 CH 4 and 13 CH 4 in the range 6500 to 12000 cm -1 measured with the Zurichinterferometer Bruker IFS 125 prototype (ZP 2001) at 80 K in a collisional-cooling cell withoptical paths ranging from 5 to 10 m. A preliminary analysis for both isotopic species wascarried out and 13 new band centers were obtained for 12 CH 4 as well as 8 new centers for13 CH 4 with an accuracy of 0.0001 - 0.0003 cm -1 from the direct experimental transitions. The13 new band centers were added to 82 previously known band centers of the 12 CH 4molecule, and a set of 26 vibrational, tetrahedral splitting, and resonance parameters wasobtained from the fit of all 95 values of band centers. The set of parameters obtainedreproduces the band centers with a root mean square deviation of about 1 cm -1 . In theanalysis symmetrized vibrational functions have been constructed in the formalism of"irreducible tensorial sets", deriving equations which describe tetrahedral splitting of thestates with the polyad quantum number N≤4. On that basis, band centers of all vibrationalstates which correspond to N≤4 (practically, up to 12000 cm -1 ) have been estimated.Comparison of the known experimental band centers of 13 CH 4 with the values of bandcenters predicted with the isotopic relations showed good agreement. In the final step, resultsobtained with the isotopic relations, were used to find new bands of the 13 CH 4 species in theregion between 6500 and 12000 cm -1 . As a result, centers of new 8 bands were determinedwith high accuracy from the direct experimental transitions by assignment of the P(1) line inthe cold spectra.References[1] O. N. Ulenikov, E. S. Bekhtereva, S. Albert, S. Bauerecker, H. Hollenstein, and M.Quack, J. Phys. Chem., A 113, 2218-2231, 2009.[2] O. N. Ulenikov, E. S. Bekhtereva, S. Albert, S. Bauerecker, H. Hollenstein, and M.Quack, Mol. Phys., 108, 1209-1240, 2010.[3] R. Marquardt and M. Quack, J. Chem. Phys.1998, 109, 10628-10643; J. Phys. Chem., A108, 3166-3181, 2004; and in Handbook of High Resolution Spectroscopy, M. Quackand F. Merkt eds., Wiley, Chichester 2011.