Search results for "diatomic molecule"
showing 10 items of 86 documents
Direct theoretical evidence of nuclear motion in H+2by means of high harmonic generation
2007
The numerical solution of the time-dependent Schro ̈dinger equation for vibrating hydrogen molecular ions in many-cycle laser pulses shows that high- order harmonic generation is sensitive to laser-induced molecular vibrations. In particular, the odd harmonic lines in the emitted spectra are surrounded by additional regular peaks whose spacing is given by the vibrational frequency of the nuclei motion. Analytical theory relates these satellite peaks to the molecular vibrations in terms of an approximated effective potentials. These results are not affected by the dimensionality of the system.
Control of the high harmonic generation spectra by changing the molecule-laser field relative orientation
2010
The time dependent Schrodinger equation of a homonuclear diatomic molecule in the presence of a linearly polarized laser field is numerically solved by means of a split-operator parallel code. The calculations are carried out by assuming a single active electron model with fixed nuclei; a simplified two-dimensional model of the system is used. The highly nonlinear response of the electron wave function to the laser electric field stimulates the molecule to emit electromagnetic radiation consisting of a wide plateau of odd harmonics of the laser field. It is shown that the emitted spectrum can be finely controlled by changing the angle between the laser electric field and the molecular axis;…
Potential construction of the B (1) 1 Π state in KCs based on Fourier-Transform spectroscopy data
2015
Abstract The paper presents an empirical pointwise potential energy curve (PEC) of the extensively perturbed B ( 1 ) 1 Π state of the KCs molecule constructed by applying an Inverted Perturbation Approach routine. The experimental term values in the energy range E ( v ′ , J ′ ) ∈ [ 14071 ; 15502 ] cm − 1 involved in the fit were based on Fourier-Transform spectroscopy data obtained with 0.01 cm−1 accuracy from laser-induced B ( 1 ) 1 Π → X 1 Σ + fluorescence spectra in the present work (654 term values) combined with 520 term values from Birzniece et al. (2012) . The data set included vibrational v ′ ∈ [ 0 , 35 ] and rotational J ′ ∈ [ 7 , 233 ] quantum numbers covering about 85% of the pot…
Spontaneous lifetimes and relaxation cross-sections of the D1Π state of NaRb
2003
Abstract The time-resolved intensity of dispersed laser induced fluorescence following the Ar + -laser D 1 Π←X 1 Σ + excitation was measured for both 23 Na 85 Rb and 23 Na 87 Rb isotopomers in a thermal cell. Spontaneous radiative lifetime values determined for v ′ ( J ′ ) rovibronic levels of the D 1 Π state in the v ′ range from 0 to 17 and J ′ from 8 to 131 varied from 22.5 to 17.3 ns. Averaged collisional quenching cross-section values of (3–6)×10 −14 cm 2 were obtained for NaRb (D 1 Π, v ′ , J ′ ) + Rb collisions from the Stern–Volmer plots.
Molecular dynamics studies of 3D quasicrystals
1993
Abstract The thermodynamic behaviour of monatomic and diatomic models of three-dimensional icosahedral quasicrystals has been studied in NVT and NPT ensembles using molecular dynamics simulations with atoms interacting via Lennard-Jones potentials. We also report on a microcanonical MD simulation of decagonal Al 65 Cu 20 Co 15 quasicrystals where an experimentally determined binary model has been used. To obtain stability in this latter case it is necessary to endow the atoms with effective pair potentials. No transitions to crystalline or amorphous phases were found for diatomic models. Monatomic models, however, display a certain stability only in the low-temperature region. In the range …
Ab initio study on the mechanism of the HCO+O2→HO2+CO reaction
2003
Abstract The gas-phase reaction HCO+O 2 →CO+HO 2 has been investigated by means of ab initio calculations. The mechanism can proceed through either a direct hydrogen abstraction or addition of O 2 to the formyl radical. The energy barriers calculated at the QCISD(T)/6-311G(2df,2p) level of theory upon QCISD/6-311G(d,p) optimized structures are, respectively, of 2.98 kcal mol −1 for the direct abstraction and of 2.26 kcal mol −1 for the addition. Thus, the results obtained show that there is not a dominant pathway in the HCO+O 2 reaction under atmospheric conditions of temperature and pressure.
Molecular mode-coupling theory applied to a liquid of diatomic molecules
2000
We study the molecular mode coupling theory for a liquid of diatomic molecules. The equations for the critical tensorial nonergodicity parameters ${\bf F}_{ll'}^m(q)$ and the critical amplitudes of the $\beta$ - relaxation ${\bf H}_{ll'}^m(q)$ are solved up to a cut off $l_{co}$ = 2 without any further approximations. Here $l,m$ are indices of spherical harmonics. Contrary to previous studies, where additional approximations were applied, we find in agreement with simulations, that all molecular degrees of freedom vitrify at a single temperature $T_c$. The theoretical results for the non ergodicity parameters and the critical amplitudes are compared with those from simulations. The qualitat…
Scaling laws for inelastic collision processes in diatomic molecules
1991
International audience
Dissociation energies within selected configuration interaction and perturbation theory
1993
Abstract Selected configuration interaction (CI) calculations and second-order perturbational theory are used to truncate systematically multireference single and double excitation CI (MRCI) expansions in the calculation of the bond dissociation energies of several systems like the single-bonded LiF molecule or the multiple-bonded N2, NO and O2 diatomic systems. The method is extended to compute the CH bond dissociation energy ofethene C2H4. It is shown how the proposed scheme (perturbation-selected MRCI (MRCI-PS)) is able to reproduce the accuracy of complete MRCI expansions with only a small number of configurations variationally evaluated.
Dunham coefficients of 14N2 from CARS measurements of high vibrational states in a low-pressure discharge
1988
Spectroscopic constants of the X1Σg+ ground state of 14N2 are deduced from CARS spectra recorded in a 4 Torr d.c. N2 glow discharge. Vibrational states up to ν = 14 have been observed but only the 11 lower levels which have a good signal-to-noise ratio have been processed. The Dunham constants that were deduced yield vibrational band centre positions in good agreement with those of Lofthus and Krupenie.