Laboratoire de Spectrométrie Physique, Université Joseph Fourier, Grenoble, France

Abstract:

To predict structure and chemical dynamics of a molecular system, the precise knowledge of the potential energy surface (PES) is required. Quantum chemical calculations and empirical force fields are powerful tools to establish landscape and topology of PES. Several experimental techniques in various combinations are capable to test the reliability of theoretical predictions and complement computational methodologies. Diffraction techniques and vibrational spectroscopy yield information about equilibrium geometry, curvature, anharmonicity of PES, while the measurement of the quantum mechanical tunneling effect probes, typically, regions far from equilibrium, i.e. the relevant trajectories along barrier separated potential minima. Neutron scattering -, NMR- and optical pump-probe measurements will be presented that trace tunneling in thermal and non-thermal equilibrium conditions, each methodology being sensitive to protons, the motions of which dominate the wide-amplitude tunneling mode in most systems.

For simple 1D motions, such as the rotation of a methyl group, these studies offer a good test for numerical modeling of the PES. However, for the transfer of a proton along a hydrogen bond, the PES is multidimensional, and the proper description of the tunneling dynamics is still a challenging enterprise and a matter of active current research.

1960-1962: Studies of Physics at the University of Göttingen; 1964: DEA de Magnétisme et Physique de Solide; 1966: Thesis 3ème Cycle, 1972: Thesis Doctorat d'Etat; 1963-1964: Stipend of the French Government; 1964-1968: Assistant at the University of Grenoble; 1973 (Jan.-Mai): Postdoctoral fellow, University of Pennsylvania; 1976 (Jan.-Dec): IBM Postdoctoral Fellow, IBM research laboratories in San Jose; 1981 - present: Maître/Directeur de Recherche at the C.N.R.S.

Editor of Chemical Physics: since 1999 (Associate Editor 1992-98); Advisory Editor of Chemical Physics Letters: since 1999.

Structure and dynamics of molecular systems in the condensed phase. Quantum motions in low-temperature solids: tunneling dynamics of proton and hydrogen atom transfer reactions and of rigid body rotations of CH₃ groups; experimental studies via laser spectroscopy and neutron scattering; theoretical description of wide-amplitude motions in multi-well potential energy surfaces.