@article {4782, title = {Mass and temperature effects on the hyperfine coupling of atomic hydrogen isotopes in cages}, journal = {Physica B-Condensed Matter}, volume = {289}, year = {2000}, note = {ISI Document Delivery No.: 330GBTimes Cited: 10Cited Reference Count: 98th International Conference on Muon Spin Rotation, Relaxation and ResonanceAUG 30-SEP 03, 1999LES DIABLERETS, SWITZERLANDEuropean Phys Soc, Paul Scherrer Inst, Eidgenoss Tech Hochschule, Univ Zurich, European Sci Fdn, Swiss Natl Sci Fdn, Neue Aargauer Bank, Sauerstoffwerk Lenzburg AG, Hamamatsu Photon, EG \& G Berthold GmbH \& Co KG, Prophysik AG, Kroger \& Co, Wenger SA, Alcatel Hochvakuum Tech GmbH, Sunrise AG, Dramer AG, Automobil \& Motoren AG}, month = {Aug}, pages = {482-486}, type = {Proceedings Paper}, abstract = {The hyperfine coupling constant A of a hydrogen isotope confined in a cage differs from its vacuum value, demonstrating that the atom acts as a probe of its environment. Room-temperature values of A for muonium in different cube-shaped Si8O12 units (T-8 units or octasilsesquioxanes), in H2O, and in D2O were determined with an accuracy of about 1 MHz. The results are compared with those obtained from high-resolution ESR on H in H2O, and D in D2O, and in different silsesquioxanes in the temperature range 40-300 K. Both the strong isotope effect and the temperature dependence are well described by a single-oscillator model of Roduner et al. (J. Chem. Phys. 102 (1995) 5989). Striking differences seen between the different silsesquioxanes and between the porous Optipur and bulk Suprasil reflect varying spatial constraints and electronic interactions. (C) 2000 Elsevier Science B.V. All rights reserved.}, keywords = {electron spin relaxation, hydrogen hyperfine coupling, MUON SPIN RELAXATION, siloxane cages}, isbn = {0921-4526}, url = {://000087953500125}, author = {Dilger, H. and Roduner, E. and Scheuermann, R. and Major, J. and Schefzik, M. and Stosser, R. and Pach, M. and Fleming, Donald G.} } @article {4408, title = {Relaxation and transport of molecular systems in the gas phase}, journal = {International Reviews in Physical Chemistry}, volume = {17}, number = {2}, year = {1998}, note = {ISI Document Delivery No.: ZQ123Times Cited: 10Cited Reference Count: 108}, month = {Apr-Jun}, pages = {185-225}, type = {Review}, abstract = {Some of the properties of gas phase relaxation and transport are reviewed with an emphasis on those properties that are due entirely to the presence of internal states in real molecular systems. The theoretical formulations of such non-equilibrium effects is based on the quantum Boltzmann equation. The conditions for the validity and the properties of this equation are reviewed. This includes a general discussion of how the combination of free molecule motion and collisions is required for the approach to global equilibrium. It is shown how the free motion is equivalent to a phase randomization of the elements of the density operator that are off-diagonal in energy. Spin relaxation and the magnetic field dependence (Senftleben-Beenakker effects) of the viscosity for a gas of diatomics are used to illustrate these aspects of the approach to equilibrium.}, keywords = {BINARY COLLISION APPROXIMATION, BOLTZMANN-EQUATION, CARTESIAN TENSORS, COEFFICIENTS, CROSS-SECTIONS, ENERGY, IRREDUCIBLE, MODERATELY DENSE GAS, MUON SPIN RELAXATION, QUANTUM KINETIC-THEORY}, isbn = {0144-235X}, url = {://000073824600003}, author = {Snider, R. F.} }