12C2H2-Ar van der Waals complex

New theoretical and experimental results on the acetylene-Ar van der Waals complex are presented and the literature is reviewed. New ab initio calculations at the MP2 level were performed using large basis sets with diffuse functions and taking into account the basis set superposition error. It was found that the structure of acetylene is not significantly altered by the complexation and that its vibrational frequencies are only slightly lowered. Finally, it was observed that the calculated properties of the complex (structure, vibrational spectrum, bond dissociation energy) are not sensitive to the structure imposed on acetylene. Experimentally, acetylene-Ar was produced in a supersonic expansion under experimental conditions corresponding to 9 K rotational temperature. Thanks to the performances of CW-CRDS detection, the Ka = 0 ← 1, 1 ← 0, and 2 ← 1 sub- bands of the v1 + v3 band could be recorded and resolved and most of their lines assigned. Upper-state rotational constants were fitted, however not including the upper Ka = 2 state, which shows K-doubling the opposite of the expected. The Lorentzian width of most line profiles sets the mean lifetime to some 7.5 ns. Local perturbations affecting line positions and/or line widths are demonstrated. Additional series of lines tentatively attributed to acetylene-Ar are discussed.© 2009 American Chemical Society.

Experimental and density functional theory study of the vibrational properties of 2-mercaptobenzimidazole in interaction with gold

The vibrational properties of the 2-mercaptobenzimidazole (MBI) molecule in interaction with gold were examined by a combined approach of FTIR measurements and density functional theory (DFT). A complete assignment of the 42 normal modes of MBI has been performed on the basis of DFT calculations at the B3PW91 level in complement to the Raman and FTIR spectra. Calculations demonstrated that, on the deprotonated MBI molecule, the negative charge is localized on the sulfur atom, favoring the formation of a gold-sulfur bond upon reaction of MBI with gold. This was confirmed by the very good agreement between the calculated spectrum and the experimental spectra of different gold-MBI compounds, indicating that the vibrational properties of adsorbed MBI are chiefly determined by the coordination through the sulfur atom. © 2006 American Chemical Society.

FT-jet spectroscopy: vibrational energy transfer in N2O

A set-up combining a high resolution Fourier transform interferometer and a quadrupole mass spectrometer with a supersonic jet expansion produced thanks to a large turbomolecular pumping unit is described. A rotational temperature close to 3 K is demonstrated. Vibration-vibration energy transfer in the expansion affecting the v2 = 1 state in N2O is monitored in the presence of various collision partners. The transfer from the v 2 = 1 state of N2O towards the quasi resonant, lower energy v2 = 1 state of OCS is demonstrated, in particular. © 2005 Elsevier B.V. All rights reserved.

Clinical Spectrum, risk factors and outcome of immune reconstitution inflammatory syndrome in patients with tuberculosis-HIV coinfection.

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First High-Resolution Analysis of the Absorption Spectrum of Propane in the 6.7-7.5 μm Spectral Region

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Reply to the comment on 'The dispersed laser induced fluorescence spectrum of gas phase C60 at 308 nm'

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