ISOIREMCO 25 years of age (revisited)

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Pressure broadening study at low temperature: application to methane

We studied the R(0) line profile in the CH4 v4 band from room temperature to 188 K with N2 as a perturber, to 100 K with O2 as perturber, and from room temperature to 15 K using He as a perturber. The N2 and O2 measurements were performed over a total pressure range of 15-110 mbar, and for the He measurements the maximum sample pressure at 15 K was 1.10 mbar. Broadening parameters were determined, taking into account the confinement narrowing (Dicke effect), and narrowing parameters, deduced from the soft or hard collision model, are compared with the dynamic friction coefficient calculated values. We also obtained preliminary values for the temperature dependence of the N2, O2 and He line broadening parameters for this transition.     

Nucleon-nucleon interaction and some reactions with3He,3H

Experimental measurements and theoretical calculations are discussed for theA = 3 nuclei. With the sum rule formalism, the need for a better bound state is investigated. Some reactions on³He and³H like electron scattering, photodisintegration,-capture involve transitions to the continuum but with the work developed by Merkuriev, Gignoux and Laverne (1976) some progress is possible. The same realisticNN interactions used for calculating the bound state wave function of the three nucleon system are incorporated in the scattering equations based on the Faddeev approach.Presented at the symposium Mesons and Light Nuclei, Bechyn, Czechoslovakia, May 27–June 1, 1985.     

Coloring of universal graphs

LetG be a graph andr a cardinal number. Extending the theorem of J. Folkman we show that if eitherr or clG are finite then there existsH with clH = clG andH (G) _r ¹ . Answering a question of A. Hajnal we show that countably universal graphU ₃ satisfiesU ₃ (U₃) _r ¹ for every finiter.     

Calculation of Franck-Condon factors including anharmonicity: simulation of the C2H4+X2B3u<--C2H4X1A(g) band in the photoelectron spectrum of ethylene

Our new simple method for calculating accurate Franck-Condon factors including nondiagonal (i.e., mode-mode) anharmonic coupling is used to simulate the C2H4+X2B3u<--C2H4X1A(g) band in the photoelectron spectrum. An improved vibrational basis set truncation algorithm, which permits very efficient computations, is employed. Because the torsional mode is highly anharmonic it is separated from the other modes and treated exactly. All other modes are treated through the second-order perturbation theory. The perturbation-theory corrections are significant and lead to a good agreement with experiment, although the separability assumption for torsion causes the C2D4 results to be not as good as those for C2H4. A variational formulation to overcome this circumstance, and deal with large anharmonicities in general, is suggested.     

Surface characterization of three marine bacterial strains by Fourier transform IR, X-ray photoelectron spectroscopy, and time-of-flight secondary-ion mass spectrometry, correlation with adhesion on stainless steel surfaces

Adhesion of bacterial strains on solid substrates is likely related to the properties of the outer shell of the micro-organisms. Aiming at a better understanding and control of the biofilm formation in seawater, the surface chemical composition of three marine bacterial strains was investigated by combining Fourier transform IR spectroscopy, X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary-ion mass spectrometry (ToF-SIMS). The D41 strain surface showed evidence of proteins, as deduced from the NH2 and NCO XPS and ToF-SIMS fingerprints; this strain was found to adhere to stainless steel, glass, or Teflon surfaces in a much higher quantity (2 orders of magnitude) than the two other ones, DA and D01. The latter are either enriched in COOH or sulfates, and this makes them more hydrophilic and less adherent to all substrates. Correlations with physicochemical properties and adhesion seem to demonstrate the role of the external layer composition, in particular the role of proteins more than that of hydrophobicity, on their adhesion abilities.