Search results for "Rotational–vibrational spectroscopy"
showing 10 items of 63 documents
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…
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…
Rovibrational transitions of H 2 by collision with H + at high temperature
2017
The H+ + H2 reaction is studied by means of both exact and statistical quantum methods. Integral cross-sections for processes initiated with rotationally excited H2(v, j = 1) to produce molecular hydrogen in its rotational ground state are reported up to a value of the collision energy of 3 eV. Rate constants for state-to-state transitions between different H2 rovibrational states are calculated up to 3000 K. Special emphasis is made on ortho/para conversion processes in which the parity j of the H2(j) states changes.
Multiconfigurational Quantum Chemistry Determinations of Absorption Cross Sections (σ) in the Gas Phase and Molar Extinction Coefficients (ε) in Aque…
2021
Theoretical determinations of absorption cross sections (σ) in the gas phase and molar extinction coefficients (e) in condensed phases (water solution, interfaces or surfaces, protein or nucleic acids embeddings, etc.) are of interest when rates of photochemical processes, J = ∫ ϕ(λ) σ(λ) I(λ) dλ, are needed, where ϕ(λ) and I(λ) are the quantum yield of the process and the irradiance of the light source, respectively, as functions of the wavelength λ. Efficient computational strategies based on single-reference quantum-chemistry methods have been developed enabling determinations of line shapes or, in some cases, achieving rovibrational resolution. Developments are however lacking for stron…
Breakdown of the Reduction of the Rovibrational Hamiltonian: The Case of S18O2F2
2009
Abstract The ground state rotational spectrum of the near-spherical top molecule S18O2F2 (sulfuryl fluoride) has been measured from 50 to 700 GHz. As for the parent isotopologue, S16O2F2 [K. Sarka, J. Demaison, L. Margules, I. Merke, N. Heineking, H. Burger, H. Ruland, J. Mol. Spectrosc. 200 (2000) 55–64], it was necessary to use a non-reduced Hamiltonian in order to obtain a satisfactory fit. It was possible to determine six quartic centrifugal distortion constants (instead of five for a standard asymmetric top) and five sextic constants (one of them not existing in the reduced Hamiltonian) could also be determined. This ground state level has also been analysed thanks to a tensorial forma…
Analysis of the rovibrational spectrum of 13CH4 in the Octad range
2013
Abstract We have measured the infrared spectrum of methane 13 CH 4 from 1100 cm −1 (33 THz), below the fundamental range, to about 12 000 cm −1 (360 THz) in the high overtone region at temperatures ranging from 80 K to 300 K by high resolution Fourier transform infrared (FTIR) spectroscopy. With instrumental bandwidths between 0.0027 cm −1 (80 MHz) and 0.01 cm −1 (300 MHz) this provides close to Doppler-limited spectra, using the Zurich prototype spectrometer (ZP2001, Bruker 125HR) combined with a multipath collisional cooling cell. Using perturbation theory and an accurate empirically adjusted potential we have computed ro-vibrational energy levels of 13 CH 4 and 12 CH 4 in the same energy…
Rovibrational Interactions in the Local-Mode Limit: The (n000) Stretching Overtone Bands of Spherical Tops
1995
Abstract We present a tensorial formalism adapted to the study of the ( n 000) rovibrational stretching states of spherical tops in the local mode limit. A local symmetrized rovibrational basis is built to take explicitly into account the fact that, in these states, the local symmetry is C 3ν rather than T d . Likewise, we introduce local rovibrational operators to build an effective Hamiltonian for these states. We then test our model by fitting the energy levels of 28 SiH 4 for 3 ≤ n ≤ 5.
Ab InitioCalculations and High-Resolution Spectroscopy of the Bending Pentad of SiH2D2in the 10–16 μm Region
1998
Abstract The SiH 2 D 2 asymmetric top has nine vibrational modes, five of them forming a pentad strongly perturbed by Coriolis interactions. High-level ab initio calculations of SiH 2 D 2 have been performed which yield numerous spectroscopic parameters related to the harmonic and anharmonic force fields. The bending pentad comprising ν 4 (A 1 ), ν 7 (B 1 ), ν 5 (A 2 ), ν 9 (B 2 ), and ν 3 (A 1 ) has been studied by high-resolution Fourier transform spectroscopy; the region 600–1050 cm −1 has been investigated with a resolution of ca. 4 × 10 −3 cm −1 . Raman BOXCARS spectroscopy has been used for the infrared inactive ν 5 band. The Raman apparatus function was 0.0054 cm −1 . Assignments of …
Development of the Dipole Moment and Polarizability Operators of Octahedral Molecules
1999
We present a development of the dipole moment and polarizability operators of octahedral molecules, using a tensorial formalism analogous to the one developed for tetrahedral molecules. These operators are involved in the calculation of the intensities of rovibrational transitions as well as in the calculation of the Stark effect. Expressions for the matrix elements are derived. Two simplified models for the study of the Stark effect in such molecules are also proposed and discussed. Copyright 1999 Academic Press.