Abstract: MATH/CHEM/COMP 2002, Dubrovnik, June 24-29, 2002
Molecular Spectroscopy of Enantiomers
and Molecular Parity Violation
1ETH Zurich (Hoenggerberg), CH 8093 Zurich, Switzerland
2Zurich University for Applied Sciences, CH 8400 Winterthur, Switzerland
Understanding molecular (ro)vibrational spectra of molecules is important for investigating the role of intramolecular vibrational energy redistribution (IVR)  in chemical kinetics and of parity violation (PV) . With the aid of high resolution infrared (IR) molecular spectroscopy combined with extensive large scale ab initio and (ro)vibrational variational calculations , it is possible to explain vibrational spectra up to high overtone excitations. Multidimensional anharmonic couplings between vibrational modes must be considered in order to understand those spectra, especially for molecules with a strongly coupled isolated CH-, CD- or CF-chromophore [1 ,3]. In contrast to vibrational IR spectroscopy, two enantiomers have the property to respond differently to polarized light; this gives rise to IR absorption spectra with absorption band intensities that differ in sign (vibrational circular dichroism, VCD).
Enantiomers of chiral molecules are usually considered to be energetically exactly equivalent. Within the framework of electroweak nuclear interaction parity violation introduces a very small energy difference. Parity violation has also been discussed in relation to biochemical homochirality. However, it has presently not been demonstrated experimentally by molecular spectroscopy which mostly neglects effects arising from PV due to its smallness. Based on
theoretical investigations, however, molecular parity violation introduces (ro)vibrational relative frequency shifts between enantiomers on the order of . It is important to reliably predict and investigate frequency shifts in chiral molecules due to parity violation which would aid future experimental investigations of this new molecular interaction. In this lecture, I will present results on those spectroscopic signatures just described for one of the simplest heavy chiral molecules, CDBrClF [3-5].
1 A. Beil, D. Luckhaus, M. Quack, J. Stohner, Ber. Bunsenges. Phys. Chem. 101 (1997) 311; M. Quack, Nova Acta Leopoldina NF 8 (1999) 137.
2 M. Quack, Angew. Chem. Int. Ed. Engl. 28 (1989) 571; M. Quack, J. Stohner, Phys. Rev. Lett. 84 (2000) 3807; M. Quack, J.Stohner, Z. Phys. Chem. NF 214 (2000) 675.
3 A. Beil, H. Hollenstein, O. Monti, M. Quack, J. Stohner, J. Chem. Phys. 113 (2000) 2701.
4 M. Quack, J. Stohner, Chirality 13 (2001) 745.
5 M. Quack, J. Stohner, (2002) to be submitted.