Narrow line photoassociation in an optical lattice

With ultracold 88Sr in a 1D magic wavelength optical lattice, we performed narrow-line photoassociation spectroscopy near the 1S0 - 3P1 intercombination transition. Nine least-bound vibrational molecular levels associated with the long-range 0u and 1u potential energy surfaces were measured and identified. A simple theoretical model accurately describes the level positions and treats the effects of the lattice confinement on the line shapes. The measured resonance strengths show that optical tuning of the ground state scattering length should be possible without significant atom loss.     

Etude du facteur d'enrichissement d'un séparateur moléculaire WATSON-BIEMANN utilisé pour l'analyse des gaz permanents

Résumé A partir de la détermination directe du facteur d'enrichissement par une méthode nouvelle adaptée à l'étude des gaz, l'influence sur celui-ci de la température et du pompage du séparateur, de la quantité injectée et du débit dans la colonne a été étudiée.

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Investigation of the enrichment factor of a WATSON-BIEMANN molecular separator used for the analysis of permanent gases

Summary Based on the direct determination of the enrichment factor by means of a new method suitable for the investigation of gases, the influence on this factor of the temperature and of the pumping of the separator, of the injected volume, and of the flow rate in the column has been investigated.

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Cet article comprend une partic des résultats de la thèse de Doctorat d'Etat ès Sciences Chimie, mention Sciences Appliquées, de Lucien Giry, eneregistrée au C.N.R.S. (A0-7755). Soutenance prévue en 1973 à l'Université Paris-Sud     

The in situ characterization and structuring of electrografted polyphenylene films on silicon surfaces. An AFM and XPS study

An atomic force microscope was used so as to structure by nanofriction films of polynitrophenylene electrografted on substrates of n-type silicon (100) with the native oxide on the top of the surface. AFM measurements of thin films thickness have been carried out in the electrolytic solution for different applied potentials during the electrografting. This investigation allows (i) to determine the relationship between the applied potential and the final thickness of electrografted polyphenylene films and (ii) to specify how the thin layers grow. XPS analysis confirmed the AFM observations on (i) the effective shaving of the grafted polymer chains under mechanical stress and (ii) the existence of a potential threshold for electrografting a polyphenylene film on silicon oxide surfaces. The presence of a residual film in the rubbed zone was attributed to stronger interactions between the first electrografted layer and the native oxide of silicon (through Si-C or/and Si-O-C bonds) than those insuring the cohesion of the multilayer (C-C and C-N bonds).     

Tip enhanced Raman spectroscopy evidence for amorphous carbon contamination on gold surfaces

We show that the origin of the spectral fluctuations frequently observed in tip enhanced Raman spectroscopy (TERS) experiments can be mainly related to the presence of surface-contaminating amorphous carbon-based species. We have monitored the spectral fluctuations originating from the sharp metallic tips used as apertureless near field probes, as well as from commonly used noble metal substrates. A correlation between the tip surface roughness and the carbon-based spectral fluctuations has been revealed. An Au-(1 1 1) bare substrate has been mapped with sub-wavelength resolution by TERS, evidencing the localization of the carbon contaminants on the surface steps and grain boundaries.     

Original ring contraction of triazine derivatives to 1,2,4-thiadiazoles

The oxidation of triazines 1 is described here. While treatment with m-CPBA or DMDO led to formation of a mixture of compounds, [TBA-OX] oxidation led exclusively to thiadiazoles 2 by ring contraction reaction.     

Measurement of optical Feshbach resonances in an ideal gas

Using a narrow intercombination line in alkaline earth atoms to mitigate large inelastic losses, we explore the optical Feshbach resonance effect in an ultracold gas of bosonic (88)Sr. A systematic measurement of three resonances allows precise determinations of the optical Feshbach resonance strength and scaling law, in agreement with coupled-channel theory. Resonant enhancement of the complex scattering length leads to thermalization mediated by elastic and inelastic collisions in an otherwise ideal gas. Optical Feshbach resonance could be used to control atomic interactions with high spatial and temporal resolution.