Search results for "Formalisme tensoriel"
showing 5 items of 5 documents
Spectroscopie des hexafluorures à nombre impair d'électrons
1995
From a theoretical point of view, a tensorial formalism adapted to the study of molecules or octahedral ions with a half-integer angular momentum has been developed for the first time. We have used here the method of projective representations, more consistent than that of double groups. A complete set of coupling coefficients and formulas, as well as the corresponding computing programs have been elaborated. This has firstly allowed to write a simple model describing the vibronic structure of colored hexafluorides. Then, somme applications of this formalism to the study of rovibronic couplings of XY6 molecules in a fourfold degenerate electronic state have been considered, especially conce…
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).
Etude des effets collisionnels dans les molécules tétraédriques. Applications au méthane perturbé par l'argon
1996
This thesis is devoted to the study of relaxational and collisional line-broadening processes in the first vibrational polyads of tetrahedral molecules. In a first part, the particular internal dynamics of such molecules is discussed. The second chapter reviews the literature on phenomena induced by intermolecular interactions involving this type of molecules. More theoretical aspects are developed in the second part. The so-called tetrahedral tensorial formalism adapted to the construction of Hamiltonians and transition moments of tetrahedral molecules is described. Main features of the infrared line-shapes theories and of semi-classical line-broadening and line-shifting calculations are a…
Rovibrational spectroscopy of ethylene : Stark effect : Application to ethylene in zeolites
2010
The objective of this report is to present a study as complete as possible of the Stark effect in the asymmetric top molecules of X2Y4 type possessing the D2h symmetry group and to apply it to the problem of the spectroscopy of the ethylene molecule trapped in a zeolite. For the first time, a tensorial formalism adapted to the study of the Stark effect for the O(3) D2h group chain was developed. In parallel, a computer package was worked out as a new generation of software called D2hTDS-ST using a simpler basis, allowing an economy in the calculation time. On the basis of the theoretical and computing tools as well as from the experimental spectra, recorded in the laboratory, we made a firs…
ROVIBRATIONAL AND STARK SPECTROSCOPY OF THE X2Y4MOLECULES. APPLICATION TO ETHYLENE
2005
This thesis is devoted to the spectroscopy of ethylene in the aim of studying the molecule trapped in zeolites. The first part deals with the tensorial model adapted to the symmetry of the isolated molecule: formalism, Hamiltonian and transition moments. To take the strong electric fields existing into zeolites into account, an extension of the model to the Stark effect is proposed in the second part. The third part describes the programs of the D2hTDS software which have been built for the calculation and analysis of X2Y4-type molecule spectra. The fourth part presents applications to the calculation and analysis of zero-field and Stark ethylene spectra. In particular, the model has been t…