Dieter Richter, geboren 1938 in Hof, war bis 2004 Professor für Kritische Literaturgeschichte an der Universität Bremen und ist Autor zahlreicher, in Deutschland und Italien erschienener Bücher zur europäischen Kulturgeschichte. Er lebt in Bremen und ist Ehrenbürger von Amalfi. Für sein Buch »Der Süden. Geschichte einer Himmelsrichtung« erhielt er den NDR Kultur Sachbuchpreis 2009.

I Rotational Tunneling I - Potentials and Phonon Interaction.- The Temperature Dependence of Rotational Tunneling - Simulation of a Quantum System at Finite Temperatures.- The Rotational Potential of Solid Nitromethane.- The Orientation of the Rotational Potential in the Crystal Frame: (NH4)2PtCl6.- Inelastic Neutron Scattering Study of Methyl Tunnelling in ?-Crystallised Toluene..- Tunnelling Spectroscopy and Dynamics of CH3 in a Homologous Series of Ketones.- NH4+ Motions in NH4MF3 Cubic Perovskites.- Spectroscopic Raman Study of Trifluoroperovskites of Ammonium Under High Pressure.- II Rotational Tunneling II - Coupled Systems.- Rotational Tunneling of Coupled Groups Studied by Inelastic Neutron Scattering..- Study of the Dipolar Proton Spin System in Lithium Acetate with NMR Dispersion Spectroscopy.- Tunnelling of Ammine Ligands in Nickel Hexammine Iodide.- The Free Rotor, NH3, in Metal Hexammine Ions.- Tunnel Spectroscopy by Dipolar-Driven NMR.K..- Zeeman-Tunnel Resonance Line Shapes in NMRRR Investigations of Rotational Tunneling..- Coupled Tunneling of Methyl Groups in Solids as Studied by Proton NMR Method..- Tunneling of CH3 Groups in Molecular Crystals of the X(CH3)n Type..- III Rotational Tunneling III - Surfaces, Isotope Effect, Matrix Isolation.- Hindered Rotation and Tunnelling of Adsorbed Species.- Rotational Tunneling of Matrix-Isolated Tetramethyl Compounds.- Rotational Excitations in (CH4)1?xKrxSolid Mixtures.- Quantum Rotation of Ammonia Molecules in Disordered Ca(NH3)6.- The Methyl Rotational Potentials of Various Isotopic Methyl Iodides and Their Coupling to Phonons.- Partially Deuterated Methyl Groups in Molecular Solids: The System 4-CH2D-C5H4N with an Original Sixfold Symmetric Barrier.- Calorimetric and Dielectric Study of PartlyDeuterated Ammonium Hexachlorostannate.- Tunneling to Reorientation Transition Effects in High Field 2H-NMR Spectra of ND4+ Ions..- IV Translational Tunneling.- Influence of Phonons and Electrons on Low-Temperature Translational Tunneling..- Quantum Diffusion of Light Interstitials in Metals.- The Influence of Electrons on the Tunneling State of a Hydrogen Atom in a Metal..- H and D Tunneling in Nb: Dependence on Defect Concentration and Trapping Center..- Sound Velocity Measurements on Hydrogen-Doped Niobium in the Superconducting and Normal States.- Quantitative Theory of the Tunnel Level Splitting for Hydrogen Trapped at Oxygen in Niobium..- Debye-Waller Peculiarity in Phonon-Assisted Tunneling.- Quantum Diffusion Above ?Debye/2..- Hydrogen Diffusion by Tunneling in Metals.- Optical Studies of Proton Tunneling and Relaxation in Benzoic Acid.- V Disordered Systems.- How Universal Is the Spectral Density of Tunneling States in Glasses?.- Very Low Frequency Elastic Loss of PMMA Below 5 K.- Ultrasonic Attenuation Study of Two-Level Systems in Neutron- Irradiated Quartz upon Heat Treatment.- The One-Dimensional Quantum Rotator H2S¯in Several Alkali Halides..- Relaxation Times of k?0 Rotons in Parahydrogen Crystals at Low Concentrations of Orthohydrogen Impurities.- Index of Contributors.

The Institut Max von Laue-Paul Langevin (ILL) in Grenoble regularly orga nizes workshops that deal with various applications of neutrons in physics, chemistry, biology and materials science. The workshop "Quantum Aspects of Molecular Motions in Solids" was jointly organized by the Institut Laue Langevin and the Institut fiir Festkorperforschung at the Kernforschungsan lage Jiilich and took place in September 1986 in Grenoble. Tunneling phenomena in molecular crystals were first observed with macro scopic methods like specific heat experiments and later also with NMR. Fi nally, the development of high resolution neutron scattering techniques like neutron backscattering led to direct spectroscopic observation of the tunnel split ground state. This breakthrough was achieved in 1975 at Jiilich. Since then the large variety of high-resolution techniques available in combination with high neutron flux have turned ILL into the leading laboratory in the field of tunneling spectroscopy. Since 1980 regular meetings of scientists involved in this topic have been organized every two years (Jiilich, Braunschweig, Nottingham) and have led to an intense exchange of ideas and experimental results. The present workshop is the fourth of this series and the first with published proceedings presenting the state of the art in this field. The eight review articles introduce scientists not involved in the subject to the actual discussion. Sessions on translational tunneling of light interstitials in metals as well as on tunneling phenomena in amorphous substances provide bridges to adjacent fields.