Martin Quack

Learn More
Parity violation leads to energy differences delta(pv)H(o)(0)=N(A)delta(pv)E of enantiomers in the femtojoule to picojoule per mole range. Recently introduced methods of electroweak quantum chemistry predict such energy differences to be one to two orders of magnitude larger than previously accepted-but still very small. How can such small energies be(More)
Just how different are the energies of left- and right-handed alanine enantiomers because of parity violation? Substantial advances in electroweak quantum chemistry have provided new answers to this question. The present, advanced calculations lead to the conclusion that numerous previous claims of L-alanine stabilization by parity violation are(More)
We review the high-resolution spectroscopic approach toward the study of intramolecular dynamics, emphasizing molecular parity violation. Theoretical work in the past decade has shown that parity-violating potentials in chiral molecules are much larger (typically one to two orders of magnitude) than anticipated on the basis of older theories. This makes(More)
We report quantitative dissociation yields for the reaction CH3OH (vOH) → nhn CH31OH induced by infrared multiphoton excitation of methanol pre-excited to various levels of the OH stretching vibration (vOH50, 1, 3, 5). The yields are measured by detecting OH using laser induced fluorescence. It is demonstrated that for low levels of pre-excitation (vOH50,(More)
We introduce the topic of fundamental symmetries of physics in relation to molecular chirality by a brief review of the development and current status of the theory of parity violation in chiral molecules. We then discuss in some detail CHBrClF (bromochlorofluoromethane) as a test case, to which the work of André Collet has contributed importantly. For this(More)
Measuring the parity-violating energy difference Δpv E between the enantiomers of chiral molecules is a major challenge of current physical-chemical stereochemistry. An important step towards this goal is to identify suitable molecules for such experiments by means of theory. This step has been made by calculations for the complex dynamics of tunneling and(More)
The analytical, full-dimensional, and global representation of the potential energy surface of NH(3) in the lowest adiabatic electronic state developed previously (Marquardt, R.; et al. J. Phys. Chem. B 2005, 109, 8439–8451) is improved by adjustment of parameters to an enlarged set of electronic energies from ab initio calculations using the coupled(More)
We report high resolution near-infrared laser spectra of water seeded in a supersonic jet expansion of argon probed by cavity ring-down spectroscopy (CRDS) in the R branch of the 2ν3 band (above 7500 cm(-1)) at several effective temperatures T < 30 K. Our goal is to study nuclear spin symmetry conservation and relaxation. For low mole fractions of water in(More)
In view of exploring possibilities for an experimental investigation of molecular parity violation we report quantum-chemical calculations of the parity-conserving and parity-violating potentials in the framework of electroweak quantum chemistry in allene C3H4 and 1,3-difluoroallene C3H2F2, which is nonplanar and axially chiral in the electronic ground(More)