CH-stretching overtone spectra of a fast rotating methyl group: 2-CH3 and 2-CHD2 pyridines.

The CH-stretching overtone spectra of the methyl group in gaseous 2-CH(3) and 2-CHD(2) methylpyridines are recorded with conventional Fourier transform near-infrared spectroscopy in the Deltav(CH) = 1-4 regions and by intracavity laser photoacoustic spectroscopy in the Deltav(CH) = 5 and 6 regions. All spectra exhibit a complex structure. They are analyzed with a theoretical model that incorporates, within the adiabatic approximation, the coupling of the anharmonic CH-stretch vibrations described by Morse potentials with the quasifree internal rotation of the methyl group and with isoenergetic combination states involving the six angle deformation modes of the methyl group.

Structure and orientation study of fusion peptide FP23 of gp41 from HIV-1 alone or inserted into various lipid membrane models (mono-, bi- and multibi-layers) by FT-IR spectroscopies and Brewster angle microscopy.

In the present work, we study the structure and the orientation of the 23 N-terminal peptide of the HIV-1 gp 41 protein (AVGIGALFLGFLGAAGSTMGARS) called FP23. The behaviour of FP23 was investigated alone at the air/water interface and inserted into various lipid model systems: in monolayer or multibilayers of a DOPC/cholesterol/DOPE/DOPG (6/5/3/2) and in a DMPC bilayer. PMIRRAS and polarized ATR spectroscopy coupled with Brewster angle microscopy and spectral simulations were used to precisely determine the structure and the orientation of the peptide in its environment as well as the lipid perturbations induced by the FP23 insertion.

Proton dynamics in the perchloric acid clathrate hydrate HClO4.5.5H2O.

In the perchloric acid clathrate hydrate HClO4.5.5H2O, the perchlorate anions are contained inside an aqueous host crystalline matrix, positively charged because of the presence of delocalized acidic protons.

Surface temperature dependence of rotational excitation of H(2) scattered from Pd(111).

Classical dynamics simulations are performed to study rotational excitation of H(2) scattered from Pd(111), taking into account energy exchange with surface phonons through a 3D surface oscillator model. We show that dynamic trapping, identified recently in the study of dissociation dynamics, plays a prominent role. The corresponding long interaction time due to several recollisions allows an efficient energy exchange between H(2) molecules and surface phonons.