Search results for "Vibrational spectroscopy"
showing 10 items of 85 documents
UV laser induced photolysis of glycolic acid isolated in argon matrices
2021
The photochemistry of matrix-isolated glycolic acid, induced by UV light, was studied by FTIR spectroscopy and B3LYPD3/6-311++G(3df,3pd) calculations. Several decomposition pathways were found to take place upon 212 nm and 226 nm wavelengths irradiation. A number of complexes formed between photoproducts were identified, among them those of formaldehyde with water, carbon monoxide and carbon dioxide as well as the H2O-CO complexes. The structure and spectroscopic assignment of the photoproducts were made comparing the experimental results with the theoretical predictions and available literature data. The observed formation of different complexes indicates various pathways for their formati…
Membrane Structure of Aquaporin Observed with Combined Experimental and Theoretical Sum Frequency Generation Spectroscopy
2021
High-resolution structural information on membrane proteins is essential for understanding cell biology and for the structure-based design of new medical drugs and drug delivery strategies. X-ray diffraction (XRD) can provide angstrom-level information about the structure of membrane proteins, yet for XRD experiments, proteins are removed from their native membrane environment, chemically stabilized, and crystallized, all of which can compromise the conformation. Here, we describe how a combination of surface-sensitive vibrational spectroscopy and molecular dynamics simulations can account for the native membrane environment. We observe the structure of a glycerol facilitator channel (GlpF)…
Regional Susceptibility in VCD Spectra to Dynamic Molecular Motions
2018
Experimental and theoretical studies of the vibrational circular dichroism (VCD) spectrum of 3-methyl-1-(methyldiphenlsilyl)-1-phenylbutan-1-ol, whose absolute configuration is key to elucidating the Brook rearrangement of tertiary benzylic α-hydroxylsilanes, are presented. It is found that the entire OH-bending region in this spectrum—a region that provides important marker bands—cannot be reproduced at all by standard theoretical approaches even though other regions are well described. Using a novel approach to disentangle contributions to the rotational strength of these bands, internal coordinates are identified that critically influence the appearance of this part of the spectrum. We s…
Microwave Fourier Transform Spectroscopy of Rovibrational Transitions in the ν 2 /ν 4 Dyads of Methane- 12 C and - 13 C
1987
The ν2/ν4 dyad-dyad spectra of 12CH4 and 13CH4 molecules in the (8÷20) GHz region have been predicted including line strengths. All transitions with γmax > 810-12 cm-1 have been observed directly using a MWFT spectrometer: six F-type transitions for 12CH4 and nine for 13CH4.
High-temperature emission spectroscopy of methane
2008
International audience; A high-enthalpy source (HES) has been developed in Rennes either to heat gases up to 2000K in local thermodynamic equilibrium (LTE) or to generate hypersonic expansions. The HES prototype has been associated with a high-resolution Bruker IFS 120 HR Fourier transform spectrometer to record emission spectra of hot gases, in LTE conditions. A series of emission spectra of methane has been obtained at 1005, 1365, 1485, 1625 and 1820K in the pentad spectral region located around 3000 cm1, at Doppler-limited resolution (0.02 cm1). Spectra have been corrected for the transmission function that strongly affects the infrared radiation emitted by the hot gas. Line-integrated a…
Complexes of Glycolic Acid with Nitrogen Isolated in Argon Matrices. II. Vibrational Overtone Excitations
2019
Structural changes of glycolic acid (GA) complex with nitrogen induced by selective overtone excitation of the &nu
Measurement and Analysis of the Raman Intensities of 12CD4
1995
0022-2852; The stimulated Raman spectrum of 12CD4 was recorded at high resolution, in the spectral range 1963 to 2260 cm(-1). Intensities of the rovibrational transitions were estimated by fitting the line profiles. The recorded elementary spectrum was 1 cm(-1) wide; all recordings were then intensity calibrated. Afterward, the relative Raman intensities were analyzed by using a polarizability model developed previously [A. Boutahar and M. Loete, Can. J. Phys. 69, 26-35 (1991); J. P. Champion, M. Loete, and G. Pierre, in ''Spectroscopy of the Earth's Atmosphere and Interstellar Molecules'' (K. Narahari Rao and A. Weber, Eds.), pp. 388-397, Academic Press, Boston. 1992]. The investigated reg…
The complete basis set Full-CI roto-vibrational spectroscopic constants of AlH, AlH+ and AlH -
2017
The spectroscopic constants of AlH, AlH + and AlH -, as well as their counterparts with H/D isotopic substitution, were obtained at the frozen core Full-CI/CBS limit and corrected for the core-correlation, relativistic and diagonal Born–Oppenheimer contributions, calculated by means of different high-level computational methods. On the basis of the obtained values, some accepted experimental result for these astrochemically relevant species is questioned.
Jet-cooled FTIR spectroscopy and analysis of the C–O stretch fundamental of Ni(CO)4
2008
Rovibrational spectra of the C–O stretch band (ν5) of Ni(CO)4 have been recorded at 0.006 cm− 1 resolution by coupling a low pressure continuous supersonic jet with a high resolution interferometer. The spectrum has been analysed thanks to the STDS software (see http://icb.u-bourgogne.fr/OMR/SMA/SHTDS/) that implements the tensorial formalism developed in the Dijon group for tetrahedral molecules. We obtain a very satisfying simulation thanks to an effective Hamiltonian expanded up to order 3. The asymmetry of the high-J lines is due to a small tetrahedral splitting and is well reproduced. The root mean square deviation is 0.96 × 10− 3 cm− 1. The Coriolis constant is somewhat larger than fo…
Rovibrational controlled-NOT gates using optimized stimulated Raman adiabatic passage techniques and optimal control theory
2009
Implementation of quantum controlled-NOT (CNOT) gates in realistic molecular systems is studied using stimulated Raman adiabatic passage (STIRAP) techniques optimized in the time domain by genetic algorithms or coupled with optimal control theory. In the first case, with an adiabatic solution (a series of STIRAP processes) as starting point, we optimize in the time domain different parameters of the pulses to obtain a high fidelity in two realistic cases under consideration. A two-qubit CNOT gate constructed from different assignments in rovibrational states is considered in diatomic (NaCs) or polyatomic $({\text{SCCl}}_{2})$ molecules. The difficulty of encoding logical states in pure rota…