486 research outputs found
INTERMOLECULAR POTENTIAL OF EXCITED ATOMS AND MOLECULES FROM MATRIX SHIFTS.
No full text J.-Y. Roncin, J. Mol. Spectry, 26, 105 (1968). J.-Y. Roncin, N. Damany and B. Vodar, Chem. Phys. Letters, March 1969.Author Institution: Laboratoire des Hautes, Pressions, C.N.R.S., Bellevue France and National Research Council of Canada Division of Pure PhysicsThe experimental shifts and broadening of far u.v. transitions of trapped species have so far permitted only qualitative conclusions concerning the dimensions of the excited In particular the matrix isolation technique has strikingly shown the profound difference in behavior of trapped molecules according to the nature of the transition; valence transitions are little affected whereas Rydberg transitions are strongly Enough experimental data are now available to attempt a quantitative estimation of the dimension of some excited states on the basis of a simple Lennard-Jones intermolecular potential . The values of and , computed for some excited states of Xe, Kr, Hg, CO, NO and , are given below: [FIGURE] During the year 1969, J.-Y. Roncin has been a Postdoctoral Fellow at the Division of Pure Physics, National Research Council of Canada, Ottawa, Canada
Quantum scattering of neon from a nanotextured surface
No full textPhonon exchange is the usual cause of decoherence in atom–surface scattering. By including quantum effects in the treatment of Debye–Waller scattering, we show that phonon exchange becomes ineffective when the relevant phonon frequencies are high. The result explains the surprising observation of strong elastic scattering of Ne from a Cu(100) surface nanotextured with a c(2 × 2) Li adsorbate structure. We extend a previous model to describe the phonon spectra by an Einstein oscillator component with an admixture of a Debye spectrum. The Einstein oscillator represents the dominant, high frequency vibration of the adsorbate, normal to the surface, while the Debye spectrum represents the substrate contribution. Neon scattering is so slow that exciting the adsorbate mode has a low probability and is impossible if the incident energy is below the threshold. Thus, adsorbate vibrations are averaged out. A theoretical discussion and calculation shows that under such circumstances the vibrations of a light adsorbate do not contribute to the Debye–Waller effect, with the result that Ne scattering at thermal energies is quantum mechanical and largely elastic, explaining the high reflectivity and the diffraction peaks observed experimentally
Le rôle des caractéristiques sectorielles dans la détermination des performances à l'exportation
No full text[eng] Alain Roncin - Sectoral characteristics and export performances. The analysis of the role of the sectoral characteristics in the explanation of the expert performances must satisfy various requirements, which are seldom satisfied simultaneously in empirical studies. These requirements are concerned first with the way the characteristics of the sectors are taken into account (level of disaggregation, reference to the effective production factor combination in the country concerned, heterogeneity of production factors) and secondly with the necessary recognition of the multiplicity of the explanatory factors involved. The analysis of the export performances of France, Germany and the U.S tends to show that the influence of the variables considered, in particular of the variables considered, in particular of the factor coefficient, in particular of the factor coefficient, is quite diffeentiated according to the country concerned. The results obtained. The results obtained from models applied to subsets of the industrial activity tend to show that it is not possible to explain all trade flows with a unique model. [fre] Alain Roncin - Le role des caractéristiques sectorielles dans la détérmination des performances à l'exportation. La recherche de l'action des caractéristiques sectorielles sur les performances à l'exportation des activités industrielles doit répondre à plusieurs conditions rarement respectées simultanément dans les études empiriques. Les conditions tiennent d'une part au mode de prise en compte des caractéristiques sectorielles (analyse à un niveau désagrégé, caractérisation des activités selon les valeurs effectives des combinaisons productives, hétérogénéité des facteurs) et d'autre part à la reconnaissance de la multiplicité des déterminants du commerce international. L'analyse des performances extérieures de la France, de la R.F.A. et des Etats Unis, met en évidence une action différenciée selon les pays des variables introduites et notamment celle des facteurs de production. Les résultats obtenus à partir des partitions de l'ensemble des activités industrielles, montrent qu' un modèle unique ne peut expliquer l'ensemble des échanges de produits manufacturés.
Dispersion insensitive, high-speed optical clock recovery based on a mode-locked laser diode
No full textAn investigation into the effects of varying levels of chromatic dispersion on a mode- locked laser diode optical clock recovery process is presented. Results demonstrate that this technique is invariant to input dispersion varying between +75 ps/nm
Cuisine et géologie / modélisation de lave et de volcans : influence du dégagement des gaz
No full text
A Large Area Fiber Optic Gyroscope on multiplexed fiber network
No full textWe describe a fiber optical gyroscope based on the Sagnac effect realized on a multiplexed telecom fiber network. Our loop encloses an area of 20 km2 and coexists with Internet data traffic. This Sagnac interferometer achieves a sensitivity of about (10-8 rad/s)/sqrt(Hz), thus approaching ring laser gyroscopes without using narrow linewidth laser nor sophisticated optics. The proposed gyroscope is sensitive enough for seismic applications, opening new possibilities for this kind of optical fiber sensors
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