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: The analysis of high-frequency electromagnetic field (HFEMF) effects on the microstructure and electrical properties of Te+ implanted (0 0 1) Si is reported. Cross-sectional high-resolution transmission electron microscopy (XHRTEM) demonstrates the formation of Te nanoclusters (NCs) embedded in the Si layer amorphized by implantation (a-Si) at fluences greater than or equal to 1 x 10(16) cm(-2). Post-implantation treatment with 0.45 MHz HFEMF leads to enlargement of Te NCs, their diffusion and accumulation at the a-Si surface and formation of laterally connected extended tellurium structures above the percolation threshold, appearing at an ion fluence of 1 x 10(17) cm(-2). AC electrical conductivity measurements show nearly four orders of magnitude decrease of impedance resistivity in this case, which is in good agreement with the results of our structural studies. The results obtained are discussed in terms of the two-phase isotropic spinodal structure. (C) 2004 Elsevier Ltd. All rights reserved.

Abstract: Based on the existing experimental data and their statistical errors, it is not possible to make a sound recommendation of the cross-section set of Campbell et al (J. Phys. B: At. Mol. Opt. Phys. 34 (2001) 1185). We comment on this paper.

Abstract: The equilibrium bond length, harmonic frequency, first and second order anharmonicity constants, rotational and centrifugal distortion constants, as well as the rotation-vibrational and centrifugal coupling constants for the ground X(2) Sigma(+) and first excited A(2) Pi states of the SiN radical have been calculated at the complete active space SCF (CASSCF), multireference CI (MRCI) and coupled cluster (CCSD(T)) levels using Dunning's correlation-consistent basis sets. The excitation energy of the A(2) Pi State has also been computed at these theoretical levels. Dipole moments of SiN in the X(2) Sigma(+) and A(2) Pi states are given. Our study shows that core correlation must be considered in order to obtain satisfactory accuracy for the spectroscopic constants.

Abstract: Organic carbocyanine dye coatings have been analyzed by time-of-flight static secondary ion mass spectrometry (TOF-S-SIMS) using three types of primary ions: Ga+ operating at 25 keV, and Xe+ and SF5+ both operating at 9 keV. Secondary ion yields obtained with these three primary ions have been compared for coatings with different layer thickness, varying from (sub)-monolayer to multilayers, on different substrates (Si, Ag and AgBr cubic microcrystals). For (sub)-monolayers deposited on Ag, Xe+ and SF5+ primary ions generate similar precursor ion intensities, but with Ga+ slightly lower precursor ion intensities were obtained. Thick coatings on Ag as well as mono- and multilayers on Si produce the highest precursor and fragment ion intensities with the polyatomic primary ion. The yield difference between SF5+ and Xe+ can reach a factor of 6. In comparison with Ga+, yield enhancements by up to a factor of 180 are observed with SF5+. For the mass spectrometric analysis of dye layers on AgBr microcrystals, SF5+ again proves to be the primary ion of choice. Copyright (C) 2004 John Wiley Sons, Ltd.

Abstract: Time-of-flight static secondary ion mass spectrometry (TOF-S-SIMS) was used to characterize thin layers of oxy- and thiocarbocyanine dyes on Ag and Si. Apart from adduct ions a variety of structural fragment ions were detected for which a fragmentation pattern is proposed. Peak assignments were confirmed by comparing spectra of dyes with very similar structures. All secondary ions were assigned with a mass accuracy better than 50 ppm. The intensity of molecular ions as well as fragment ions has been studied as a function of the type of organic dye, the substrate, the layer thickness and the type of primary ion. A large yield difference of two orders of magnitude was observed between the precursor ions of cationic carbocyanine dyes and the protonated molecules of the anionic dyes. Fragment ions, on the other hand, yielded similar intensities for both types of dye. As the dye layers deposited on an Ag substrate yielded higher secondary ion intensities than those deposited on a Si substrate, the Ag metal clearly acts as a promoting agent for secondary ion formation. The effect was more pronounced for precursor signals than for fragment ions. The promoting effect decreased as the deposited layer thickness of the organic dye layer was increased. Copyright (C) 2003 John Wiley Sons, Ltd.