Search results for "Molecular spectroscopy"
showing 7 items of 27 documents
Algebraic study of pyramidal molecules in the very excited vibrational states.
2005
In the frame of the algebraic formalism U(p+1), we developed the method to build a vibrational Hamiltonian corresponding to a set of three identical oscillators. In order to test the model, we apply it to the molecules of stibine and arsine. We introduce a supplementary intermediate group K(3) inspired by the similar formalism used in nuclear physics. This group K(3) gives additional labels for classification of the energy levels. The eigenvalues of these invariant operators distinguish the local states of the molecule. Then we study the coupling of the vibrational modes of stretching and bending for the non plane XY3 molecules. We present the construction of an algebraic operator of coupli…
Detection of bias errors in ETAASDetermination of copper in beer and wine samples
2005
A method that evidences changes in the shape of the absorbance profiles obtained by graphite furnace atomic absorption spectrometry (ETAAS) is proposed. The method is based upon the apparent content curves model previously described for molecular spectroscopy and it permits the detection of possible sources of bias errors. Moreover, a procedure that allows to detect the existence of constant and/or proportional errors is also described. Both models has been applied to the determination of copper in wine and beer samples with and without pre-treatment of the samples. Results obtained evidence the usefulness of the proposed models.
Analytical measurements of fission products during a severe nuclear accident
2018
The Fukushima accident emphasized the fact that ways to monitor in real time the evolution of a nuclear reactor during a severe accident remain to be developed. No fission products were monitored during twelve days; only dose rates were measured, which is not sufficient to carry out an online diagnosis of the event. The first measurements were announced with little reliability for low volatile fission products. In order to improve the safety of nuclear plants and minimize the industrial, ecological and health consequences of a severe accident, it is necessary to develop new reliable measurement systems, operating at the earliest and closest to the emission source of fission products. Throug…
Symmetry-adapted tensorial formalism to model rovibrational and rovibronic spectra of molecules pertaining to various point groups
2004
International audience; We present a short review on the tensorial formalism developed by the Dijon group to solve molecular spectroscopy problems. This approach, originally devoted to the rovibrational spectroscopy of highly symmetrical species (spherical tops) has been recently extended in several directions: quasi-spherical tops, some symmetric and asymmetric tops, and rovibronic spectroscopy of spherical tops in a degenerate electronic state. Despite its apparent complexity (heavy notations, quite complex mathematical tools), these group theoretical tensorial methods have a great advantage of flexibility: a systematic expansion of effective terms for any rovib- rational/rovibronic probl…
Error propagation from line parameters to spectra simulations. Illustration on high temperature methane.
2010
Astrophysical investigations generally need both complete and accurate spectroscopic databases. Despite continuous efforts in experimental and theoretical spectroscopic investigations, the lack of data in some spectral regions of interest is one of the main limitation of the presently available spectroscopic databases. Unfortunately information about missing data relevant to specific experimental conditions is rarely directly accessible from spectroscopic databases (focusing naturally on available data). Such information relies essentially on theoretical investigations which are equally limited to the present state of the art of modelling. The purpose of the talk is to show how multi-resolu…
From the spherical top to the asymmetric top
2004
This habilitation report presents a synthesis of my research work during the last 14 years. I have distinguished my experimental activities (part III), my theoretical work on the spectroscopy of quasi-spherical tops (part IV) and that concerning the spectroscopy of molecules trapped in solids (part V).
Applications of Quantum Chemistry in Spectroscopy: Molecules, Complexes of Van der Waals, trapped Molecules
2009
I described in this memory my activities as a researcher at Tomsk well before 2003, in succession to the State University of Tomsk in the Faculty of Physics, Institute of Physics of Siberia, and the Institute of 'Atmospheric Optics, in France since then, mostly at the University of Bourgogne (ICB), but also at the University of Lille I (PhLAM) and the University of Marne-la-Vallée (LCT). Part of my work has been dedicated to the evaluation by calculating ab initio of rovibrational constants for quasi-spherical molecules. The centrifugal distortion constants and the dipole moment of the molecule SO2F2 were calculated to validate the tensor theory and interpreter the spectrum. I twas shown th…