Quasiparticle contribution to heat carriers relaxation time in DyBa2_2Cu3_3O7−x_{7-x} from heat diffusivity measurements

It is shown that the controversy on phonons or electrons being the most influenced heat carriers below the critical temperature of high-T$_c$ superconductors can be resolved. Electrical and thermal properties of the same DyBa$_2$Cu$_3$O$_{7-x}$ monodomain have been measured for two highly different oxygenation levels. While the oxygenated sample DyBa$_2$Cu$_3$O$_{7}$ has very good superconducting properties ($T_c=90$ K), the DyBa$_2$Cu$_3$O$_{6.3}$ sample exhibits an insulator behavior. A careful comparison between measurements of the {\bf thermal diffusivity} of both samples allows us to extract the electronic contribution. This contribution to the relaxation time of heat carriers is shown to be large below $T_c$ and more sensitive to the superconducting state than the phonon contribution.Comment: 13 pages, 6 figure

Electron short-wave phonon scattering in crystals with chalcopyrite lattice

Electron short-wavelength phonon scattering is an effective channel for energy relaxation in crystals with a pseudo-direct optical gap. The equilibrium parameters of crystal structures and spectra of electrons and phonons in the ternary chalcopyrite compounds ZnSiP2 and ZnGeP2 are calculated self-consistently in good agreement with available experimental and theoretical calculations. The ab initio probabilities of phonon-assisted intervalley scattering of electrons in the conduction bands of the pseudo-direct-gap compounds ZnSiP2 and ZnGeP2 between the central Γ minima and the lowest lateral minima (valleys) at the T and N points have been calculated using the density functional perturbation theory. Electron–phonon scattering rates associated with intervalley phonons are calculated. Coupling constants for intervalley phonons in the chalcopyrite phosphides are close to their values in Si, Ge, and in the binary analog GaP.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Murnaghan's equation of state for the electronic ground state energy

International audienceIn this work, we study the formulae of Murnaghan's equation of state, reported in the literature and used to fit the theoretical electronic ground state energy and obtain thermodynamical quantities like the bulk modulus. We find that the expression of the energyversus- volume dependence, obtained by a straightforward integration of the pressure-versus-volume equation of state, does not satisfy the requirement of independent parameters imposed by the least-square fitting process. Instead, a change in the definition of the integration constant leads to a well-behaved fitting function, which is recommended in order to obtain reliable thermodynamical quantitie

Toward an Improved Ground State Potential Energy Surface of Ozone

A systematic study of the ozone potential energy surface was performed by means of high level ab initio techniques. The methods include icMR-CISD and icMR-AQCC with all electrons correlated using a full valence CAS reference space and basis sets up to sextuple-ζ quality along with extrapolation to the complete basis set limit. We computed a dense 3D grid as well as 1D cuts along stretching and bending coordinates around the open (C(2v)) equilibrium structure as well as along the minimum energy path to dissociation including the transition state and the van der Waals minimum region. The detailed analysis of our results confirms earlier calculations by the Schinke group and assures that these are not biased by deficiencies of the basis set, lack of relativistic corrections, or core correlation effects. Finally, we discuss possible sources of error that may explain the remaining discrepancies compared to experimental findings

Fourier transform and high sensitivity cw-cavity ringdown absorption spectroscopies of ozone in the in the 6030-6130 cm –1 region. First observation and analysis of the 3v1 + 3v3 and 2v2 + 5v3 bands

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Modelling of the 2ν1- ν1 and ν1 band transitions of 13CH4 using high resolution Raman spectroscopy measurements

The pump-probe technique for investigating vibrationally excited states via high resolution Raman spectroscopy was applied to CH methane isotopologue. The dipole transitions between A totally symmetric vibrational states are not active in IR spectra but these states can be efficiently studied using selective high resolution Raman spectroscopy. 80 vibration-rotation transitions, most of which belong to the 2ν– ν band have been assigned in the observed Raman spectra reported in this work. Including the Raman transitions in the simultaneous data fit improves the accuracy of the effective Hamiltonian and also rovibrational upper state levels of the ν, 2ν and 2ν (A) bands. A more accurate model of the ν vibration-rotation transitions improves the interpretation of the temperature dependence of Raman spectra involving the Pentad and Tetradecad polyads.Part of the research was performed at Institute of Monitoring of Climatic and Ecological Systems under contract of Russian Science Foundation (RSF), grant No. 19-77-10046. The research at the V.E. Zuev Institute of Atmospheric Optics was supported by the Ministry of Science and Higher Education of the Russian Federation (V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Sciences). The supports of the CNRS (France) in the frame of “Laboratoire International Associé SAMIA”, of IDRIS / CINES computer centers of France and of the ROMEO computer center Reims-Champagne-Ardenne are acknowledged. R.Z. Martínez, D. Paredes-Roibás and D. Bermejo acknowledge the funding received from Project FIS2017-84391-C2-1-P of Ministerio de Economía y Competitividad

Non-LTE spectroscopy of the tetradecad region of methane recorded in a hypersonic flow

International audienceLaboratory spectroscopic data is essential for the modeling of hot exoplanet atmospheres, since molecules such as methane, a major component of hot-Jupiter-type exoplanet atmospheres, have a complex vibrational energy structure that makes computational predictions difficult at high temperatures for ro-vibrational transitions involving highly excited vibrational sates. To better inform line lists used in radiative transfer modeling, the ro-vibrational spectrum of methane has been recorded in the tetradecad region between 1.7 and 1.65 μm (5880–6060 cm−1) through non-local thermodynamic equilibrium (non-LTE) cavity ringdown spectroscopy (CRDS). Non-LTE conditions, characterized by a low rotational temperature (∼39 K) and a high vibrational temperature (up to 1130 K), have been obtained by hypersonic expansion of a pre-heated mixture of argon and methane in a contoured Laval nozzle. The high vibrational temperature increases the intensity of new hot bands, while the very low rotational temperature greatly simplifies their rotational structure, thus facilitating their identification. A close comparison of the recorded CRDS data to the TheoReTS database reveals both inefficient vibrational relaxation between polyads and efficient vibrational relaxation between vibrational states forming a polyad. These effects result in an overpopulation of the lowest vibrational energy level of each polyad, an effect not widely currently incorporated in non-LTE radiative transfer models. A series of new hot band transitions originating from the pentad and octad polyads were assigned and are provided as a line list for use in future databases. © 2023 Elsevier Inc

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International audienc

The GEISA spectroscopic database: Current and future archive for Earth and planetary atmosphere studies

The development of Gestion et Etude des Informations Spectroscopiques Atmospheriques (GEISA: Management and Study of Spectroscopic Information) was started over three decades at Laboratoire de Meteorologie Dynamique (LMD) in France. GEISA is a computer accessible spectroscopic database, designed to facilitate accurate forward radiative transfer calculations using a line-by-line and layer-by-layer approach. More than 350 users have been registered for on-line use of the GEISA facilities. The current 2003 edition of GEISA (GEISA-03) is a system comprising three independent sub- databases devoted respectively to: line transition parameters, infrared and ultraviolet/visible absorption cross-sections, microphysical and optical properties of atmospheric aerosols. Currently, GEISA is involved in activities related to the assessment of the capabilities of IASI (Infrared Atmospheric Sounding Interferometer on board of the METOP European satellite) through the GEISA/IASI database derived from GEISA. The GEISA-03 content is presented, placing emphasis on molecular species of interest for Earth and planetary atmosphere studies, with details on the updated 2008 archive underway. A critical assessment on the needs, in terms of molecular parameters archive, related with recent satellite astrophysical missions is made. Detailed information on free on-line GEISA and GEISA/IASI access is given at http://ara.lmd.polytechnique.fr and http://ether.ipsl.jussieu.fr