Abstract: The quartic force field of thioformaldehyde has been calculated ab initio using large basis sets and augmented coupled cluster methods. Calculated fundamentals are in excellent agreement with experiment, as is the most important Coriolis coupling constant. Computed values for the anharmonicity, rovibrational coupling, and centrifugal distortion constants of the four isotopomers (H2CS)-S-32, (H2CS)-S-34, (HDCS)-S-32, and (D2CS)-S-32 have been reported. Predictions have been made for all vibrational transitions from the ground state to excited states with at most two quanta for these isotopomers, both using second-order perturbation theory corrected for Darling-Dennison resonance and using vibrational SCF-CI calculations. For (D2CS)-S-32, perturbation theory performs quite well; for the other isotopomers, performance is poorer for states involving excitation of the out-of-plane bend and, for the (H2CS)-S-32 and (H2CS)-S-34 isotopomers, also for the antisymmetric bend that is in severe Coriolis resonance with it. A possible explanation has been suggested. (C) 1994 Academic Press, Inc.

Abstract: Twin-domains of a b.c.c. crystalline phase with a = 0.29 nm have been found in a surface layer on surfaces of Al-Co decagonal quasicrystals and the coexisting tau(2)-Al13Co4 crystalline approximant. These surface layer domains are introduced during the preparation of electron microscopy thin films by ion milling.

Abstract: Magnetoreflectivity measurements of the 1s and 2s exciton energies in a CdTe/Cd1-xMnxTe superlattice have been made in magnetic fields up to 45 T, showing the resonant polaron coupling of electrons to LO phonons. Strong reflectivity features are seen for both the 1s and 2s excitons, which show a strong field-dependent spin splitting due to the dilute magnetic barriers. At B-z=0, the 2s exciton feature is observed lying 18 meV above the Is state, and is shifted upward in energy by the magnetic fields. No resonant behavior occurs when the 2s state passes through the LO-phonon energy of 21 meV, but at higher fields of around 20 T, the resonances for both spin states (sigma(+/-)) of the 2s exciton broaden and show a strong anticrossing behavior. These experiments are shown to be in excellent agreement with a theoretical treatment which includes the resonant polaron coupling of the electrons alone. Both experiment and theory demonstrate an extremely strong resonant splitting of the 2s exciton states of approximately 11 meV, which is over 50% of the LO-phonon energy. The dominance of single-particle polaron coupling is attributed to the relative sizes of the polaron (35 Angstrom A) and the exciton (50 Angstrom A) radius.

Abstract: In this paper a particularly simple but efficient method is presented by which samples of alkali-doped C-60 materials or other air-sensitive materials can be prepared and transferred into a transmission electron microscope for direct observations and investigations. Flexible, transparent glove bags are used which are filled to a slight overpressure with dry nitrogen. Under this protective atmosphere, the air-sensitive sample is mounted in the specimen holder and inserted in the vacuum of the electron microscope. Rb6C60 which is prepared and transferred into the microscope in this way has been investigated by transmission electron microscopy (TEM). The results confirm the bcc structure and especially the location of the rubidium atoms.