619 research outputs found
The CO A-X System for Constraining Cosmological Drift of the Proton-Electron Mass Ratio
The band system of carbon monoxide,
which has been detected in six highly redshifted galaxies (), is
identified as a novel probe method to search for possible variations of the
proton-electron mass ratio () on cosmological time scales. Laboratory
wavelengths of the spectral lines of the A-X (,0) bands for have
been determined at an accuracy of
through VUV Fourier-transform absorption spectroscopy, providing a
comprehensive and accurate zero-redshift data set. For the (0,0) and (1,0)
bands, two-photon Doppler-free laser spectroscopy has been applied at the accuracy level, verifying the absorption data. Sensitivity
coefficients for a varying have been calculated for the CO A-X
bands, so that an operational method results to search for -variation.Comment: 7 pages (main article), 3 figures, includes supplementary materia
Genèse et fonctionnement des sols en milieu équatorial
La genèse des sols en milieu équatorial présente une forte composante biologique. La structure générale des profils ferrallitiques s'explique par le recyclage biologique des principaux éléments intervenant dans les équilibres minéraux-solutions, et la plupart des minéraux secondaires des sols ferrallitiques sont en rééquilibrage constant avec les conditions du milieu. La genèse des podzols est liée à une exportation précoce des composés organo-métalliques formés dans les horizons de surface, dépendante de la dynamique de l'eau à l'échelle des systèmes. (Résumé d'auteur
VUV Fourier-transform absorption study of the Lyman and Werner bands in D2
An extensive survey of the D2 absorption spectrum has been performed with the
high-resolution VUV Fourier-transform spectrometer of the DESIRS beamline at
the SOLEIL synchrotron. The frequency range of 90 000-119 000 cm-1 covers the
full depth of the potential wells of the B 1{\Sigma}+u, B' 1{\Sigma}+u, and C
1{\Pi}u electronic states up to the D(1s) + D(2\ell) dissociation limit.
Improved level energies of rovibrational levels have been determined up to
respectively v = 51, v = 13, and v = 20. Highest resolution is achieved by
probing absorption in a molecular gas jet with slit geometry, as well as in a
liquid helium cooled static gas cell, resulting in line widths of ~0.35 cm-1.
Extended calibration methods are employed to extract line positions of D2 lines
at absolute accuracies of 0.03 cm-1. The D1{\Pi}u and B" 1{\Sigma}+u electronic
states correlate with the D(1s) + D(3\ell) dissociation limit, but support a
few vibrational levels below the second dissociation limit, respectively v =
0-3 and v = 0-1, and are also included in the presented study. The complete set
of resulting level energies is the most comprehensive and accurate data set for
D2. The observations are compared with previous studies, both experimental and
theoretical.Comment: 13 pages, 6 figures. The second set of Tables (Tables I-IV after the
references), is auxiliary materia
Lateritic weathering of pyroxenites at Niquelandia, Goias, Brazil : the supergene behavior of nickel
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