Ab initio non-adiabatic study of the 4psigma B'' 1Sigma u state of H2

International audienceFully ab initio non-adiabatic multichannel quantum defect calculations of the 4psigma B'' 1∑u energy levels, line intensities and widths, based on the latest quantum-chemical clamped-nuclei calculations of Wolniewicz and collaborators are presented for H2. The B" state corresponds to the inner well of the ? state. The B'' v >= 1 levels are rapidly predissociated through vibrational coupling with the 3psigma B' 1Sigma u continuum so that coupled-equation calculations become unstable. Multichannel quantum defect theory, on the other hand, is demonstrated to be particularly suited to this situation. Experimental data as level energies, line intensities and dissociation widths were revisited and corrected. Reinvestigating previously published spectra, several new lines were assigned

Vector properties in photodissociation: Quantum treatment of the correlation between the spatial anisotropy and the angular momentum polarization of the fragments

The dependence of the angular momentum polarization (orientation and alignment) of the fragments on the direction of ejection k, is studied quantum mechanically for molecular photodissociation into two fragments of which one carries an angular momentum j. Explicit expressions in terms of the transition matrix elements for electronic excitation into the final dissociative states are given in the axial-recoil limit and for different photon polarizations. The importance of interference effects due to coherent excitation of dissociative states with different helicity quantum numbers (the projection Ω of j on the recoil direction k) is stressed. It is shown that not only absolute magnitudes but also relative phases of individual transition matrix elements can be determined separately if the spatial anisotropy of the angular momentum polarization is measured. © 1994 American Institute of Physics.Peer Reviewe

Photon-excitation photon-emission maps (PhexPhem maps) with rovibronic resolution as a data base for theory and astrophysics part I: method and first results for H2

International audienceDispersed fluorescence of wavelengths between 75 and 180 nm has been recorded after excitation of room temperature H 2 X 1 Σ + g (v = 0) by narrow bandwidth monochromatized synchrotron radiation. Spectra have been taken in the exciting-photon energy range between 11 and 18 eV for discrete energy steps of 2.5 meV at a bandwidth of about 10 meV. The exciting-photon energy bandwidth has been narrow enough to induce transitions between individual rovibronic states. The resolution in the dispersed fluorescence detection was partly sufficient to resolve fluorescent transitions between individual rovibronic states. The recorded intensities are presented as two-dimensional photon-excitation photon-emission (PhexPhem) maps. They give a complete overview of experimental dispersed VUV/ FUV fluorescence spectra of H 2 for these excitation energies, covering excitation from H 2 X 1 Σ + g (v = 0) to all known singly excited states. The presented proof of principle experiments show a way to generate spectroscopic reference data for theory benchmarking and the interpretation of astrophysical observations

Experimental and theoretical study of the npπ1Πu- (n⩾4n⩾4) excited states of D2: absolute absorption cross sections and branching ratios for ionization, dissociation and fluorescence

International audienceThe absolute absorption cross section and the branching ratios for the competing decay channels fluorescence, dissociation, and ionization of photoexcited long-lived View the MathML source1Πu- superexcited molecular levels in D2 have been measured with a spectral resolution of 0.001 nm from the ionization threshold of D2 up to the D(n=1n=1)+D(n=3n=3) dissociation limit. The experimental energies and absorption line intensities are compared with fully ab initio multichannel quantum defect theory (MQDT) calculations [1] which are based on quantum-chemical potential energy curves and transition moments of Wolniewicz and collaborators [2] and [3]. The overall agreement between experiment and theory is good. The branching ratios for the competing decay channels are also reproduced by the calculations including their substantial variations from level to level. A comparison of the vibronic interactions in the isotopomers H2 and D2 is made

VUV Fourier-Transform absorption study of the npπnpπ1Πu-,v,N←X1Σg+,v″=0,N″ transitions in D2

International audienceThe DESIRS beamline of the SOLEIL synchrotron facility, equipped with a vacuum ultraviolet Fourier-Transform spectrometer has been used to measure Q(N″)Q(N″) (N-N″=0N-N″=0) absorption transitions of the D2 molecule. Some 212 Q-lines were assigned and their transition frequencies determined up to excitation energies of 137000 cm-1 above the ground state, thereby extending the earlier work by various authors, and considerably improving the spectral accuracy (<0.1<0.1 cm-1). The assignments have been aided by first principles multichannel quantum defect theory (MQDT) calculations which also provide predictions of the autoionization widths of the upper levels

Synchrotron vacuum ultraviolet radiation studies of the D-1 Pi(u) state of H-2 (Correction of vol 133, 144317, 2010)

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Publisher's Note: ``Synchrotron vacuum ultraviolet radiation studies of the D 1Piu state of H2'' [J. Chem. Phys. 133, 144317 (2010)]

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VUV Spectroscopic Study of the D 1Π u State of Molecular Deuterium

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VUV Spectroscopic Study of the D 1Π u State of Molecular Deuterium

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