Benoit Tremblay

The (CH2)2O-H2O hydrogen bonded complex. Ab Initio calculations and Fourier transform infrared spectroscopy from neon matrix and a new supersonic jet experiment coupled to the infrared AILES beamline of synchrotron SOLEIL.

A series of hydrogen bonded complexes involving oxirane and water molecules have been studied. In this paper we report on the vibrational study of the oxirane-water complex (CH(2))(2)O-H(2)O. Neon matrix experiments and ab initio anharmonic vibrational calculations have been performed, providing a consistent set of vibrational frequencies and anharmonic coupling constants. The implementation of a new large flow supersonic jet coupled to the Bruker IFS 125 HR spectrometer at the infrared AILES beamline of the French synchrotron SOLEIL (Jet-AILES) enabled us to record first jet-cooled Fourier transform infrared spectra of oxirane-water complexes at different resolutions down to 0.2 cm(-1). Rovibrational parameters and a lower bound of the predissociation lifetime of 25 ps for the v(OH)(b) = 1 state have been derived from the rovibrational analysis of the ν(OH)(b) band contour recorded at respective rotational temperatures of 12 K (Jet-AILES) and 35 K (LADIR jet).

Bonding Nature and Vibrational Signatures of Oxirane:(Water)n=1–3. Assessment of the Performance of the Dispersion-Corrected DFT Methods Compared to the ab initio Results and Fourier Transform Infrared Experimental Data

Spectroscopic properties of 1:n complexes (n = 1, 2, and 3) formed between an oxirane molecule and water clusters have been evaluated using experimental techniques (FTIR spectroscopy using a new supersonic jet experiment coupled to the infrared AILES beamline of synchrotron SOLEIL and also cryogenic neon matrix device) and theoretical approaches (SAPT, ab initio, DFT, and topological analyses). From a systematic comparison between the theoretical results (obtained with both wave function based methods and several newly hydrogen bonded adapted functionals) with the available experimental results on the studied compounds, it was concluded that only the wave function based methods (particularly coupled clusters ones) are able to well describe these compounds, while the newly hydrogen bonded adapted functionals (long-range and/or dispersion-corrected ones and also double hybrids) cannot adequately describe all the spectroscopic properties in a systematic way. The MP2 method, although more expensive than DFT, still offers a reliable method to study both isolated molecules and hydrogen bonded complexes provided the contribution of the dispersion energy in total energy is properly taken into account. The nature of interaction between oxirane and water molecules has been analyzed using the symmetry adapted perturbation theory (SAPT) method. It was evidenced that the water-oxirane interaction corresponds to the hydrogen-bonded systems with a large contribution of the dispersion energy. The nature of the oxirane-water bonding has been studied using two topological methods: atoms in molecules and electron-localization function (ELF). Geometrical structures of the titled complexes were rationalized from the spatial arrangement of ELF attractors. Secondary interaction was also accounted for the bond critical points found at H(oxirane)···O(water) bond paths.

Vibrational spectra and structure of the KO2 complex in solid argon. A far-infrared study

Abstract The observation of new fundamental frequencies for the potassium superoxide KO 2 is reported for different isotopic species: ν 3 of 39 K 16 O 2 , 39 K 18 O 2 and 39 K 16 O 18 O, and ν 2 of 41 K 16 O 2 , 41 K 18 O 2 , 41 K 16 O 18 O and 39 K 17 O 18 O. Using these values and a fixed OO internuclear distance, we calculated the geometry and force constants from a harmonic force field. We estimated an OKO angle of 37° ± 2°, and a KO internuclear distance of the order of 2.10±0.14 A. These values disagree with previous theoretical determinations.

Conformational Landscape of the 1/1 Diacetyl/Water Complex Investigated by Infrared Spectroscopy and ab Initio Calculations

The complexes of diacetyl with water have been studied experimentally by Fourier transform infrared (FTIR) spectroscopy coupled to solid neon matrix and supersonic jet, and anharmonic ab initio calculations. The vibrational analysis of neon matrix spectra over the 100-7500 cm-1 infrared range confirms the existence of two nearly isoenergetic one-to-one (1/1) diacetyl-water S1 and S2 isomers already evidenced in a previous argon matrix study. A third form (S3) predicted slightly less stable ( J. Mol. Mod. 2015 , 21 , 214 ) is not observed. The correct agreement obtained between neon matrix and anharmonic calculated vibrational frequencies is exploited in several cases to derive band assignments for the vibrational modes of a specific isomer. Thereafter, theoretical xij anharmonic coupling constants are used for the attribution of combination bands and overtones relative to the 1/1 dimer. Finally, the most stable isomer of the one-to-two (1/2) diacetyl-water complex is identified in the OH stretching region of water on the grounds of comparison of experimental and calculated vibrational shifts between water dimer and the three most stable 1/2 isomers.

155 Research to support the implementation of a public health policy on helmet use in alpine ski areas

Background From 1995 to 2000, the rate of injury in Québec, Canada, ski areas significantly increased. This problem coincided with an increase in the number of snow-parks. Before suggesting injury prevention measures, some questions had to be answered: Are helmets effective? Does helmet use result in a false-sense of security? Can head-neck-helmet biomechanics increase spinal injury risk? Do expert skiers and snowboarders need a helmet? Is there an increased risk of serious injury in snow-parks? The aim of this paper is to outline how a series of epidemiologic studies significantly contributed to support the implementation of important safety measures in alpine ski areas. Methods A series of case-control studies were undertaken. They were based on the information gathered through ski patrol injury report forms (IRF). Depending on the specific study, between 4,377 and 97,408 IRFs were analysed. Results The results of these studies suggest that: helmets are effective in reducing the risk of any head injury (adjusted odds ratio [AOR] = 0.71; 95% CI: 0.55–0.92); helmet use is not associated with a false-sense of security leading to riskier behaviours; helmets do not increase the risk of neck injuries; expert alpine skiers are at greater risk of head-neck injuries compared with beginners (AOR = 1.86, 95% CI: 1.65–2.10); for skiers (AOR = 1.36; 95% CI: 1.21–1.53) and snowboarders (AOR = 1.14, 95% CI: 1.05–1.23), injuries sustained in snow-parks compared with other slopes are more likely to require ambulance evacuation. Conclusions Considering this evidence, the Québec Government modified a provincial regulation to make compulsory the use of helmets in all snow-parks. The Québec Ski Areas Association and the Québec Government also implemented a practical guide for building and operating snow-parks. Results show a reduction in the rates of head-neck injury from 1997–1998 season (5.07/10,000 visits; 95% CI: 4.84–5.31) to 2012–2013 season (3.27/10,000 visits; 95% CI: 3.13–3.41).