To date no experiment has reached the level of sensitivity required to observe weak nuclear force induced parity violation (PV) energy differences in chiral molecules. In this paper, we present the approach, adopted at Laboratoire de Physique des Lasers (LPL), to measure frequency differences in the vibrational spectrum of enantiomers. We review different spectroscopic methods developed at LPL leading to the highest resolutions, as well as 20 years of CO 2 laser stabilization work enabling such precise measurements. After a first attempt to observe PV vibrational frequency shifts using sub-Doppler saturated absorption spectroscopy in a cell, we are currently aiming at an experiment based on Doppler-free two-photon Ramsey interferometry on a supersonic beam. We report on our latest progress towards observing PV with chiral organo-metallic complexes containing a heavy rhenium atom.

By a Plasma Enhanced Chemical Vapor Deposition process (PECVD), we are able to prepare nitrogenated amorphous carbon materials around room temperature from methane and nitrogen gas as precursors. We have also used chlorine gas as an additive to reduce the hydrogen content of our samples. Starting from the “as-deposited” materials, we have investigated their thermal stability by successive heat treatments up to 1400 °C. These compounds suffer a weight loss mostly due to the hydrogen departure. They become nonfusible and it turns out that nitrogen, chemically bound to sp2 hybridized carbons, induces some changes in the physical properties. In order to understand the relationship between the local structural organization and the physical characteristics, we have investigated different spectroscopic techniques such as Nuclear Magnetic Resonance, IR Absorption, and X-ray Photoelectron Spectroscopy. We have also investigated several transport properties: (i) The dc electrical conductivity shows a kind of metal/insulator transition around 700 °C. The temperature dependence for the conductive samples gives evidence for a pseudogap associated with the presence of localized states, (ii) The thermal conductivity exhibits, for the as-deposited compound, a very low value varying slowly with temperature; its magnitude as well as its temperature dependence, characteristic of noncrystalline materials, are modified by the annealing process. Finally, an electronic band model is proposed, explaining the structural evolution through a kind of Mott–Anderson pseudotransition.

Deuterium solid state NMR and freeze fracture electron microscopy experiments have been carried out in the lamellar Lα phase of the water−sodium dodecyl sulfate−octanol system. Within the lamellar phase two types of bilayer organizations have been found. At high surfactant and alcohol concentrations, the lamellar phase is made of a stack of flat parallel bilayers while in the dilute part, it consists of multilayered vesicles of large radius (ca. 10 000 Å). These latter structures, commonly called spherulites, which appear spontaneously at low octanol contents and/or for high water dilution, can be described as textural defects of the lamellar phase. The location of this onion-like structure region is discussed within the framework of the membrane elasticity theory. As a side result, the presence of 33% glycerol in some of the freezefracture experiments is shown to barely affect the bending modulus of the film but rather disorder the molecular packing of the bilayers.

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We present a method for accurate mid-infrared frequency measurements and stabilization to a near-infrared ultra-stable frequency reference, transmitted with a long-distance fibre link and continuously monitored against state-of-the-art atomic fountain clocks. As a first application, we measure the frequency of an OsO 4 rovibrational molecular line around 10 µm with an uncertainty of 8 × 10 −13 . We also demonstrate the frequency stabilization of a mid-infrared laser with fractional stability better than 4 × 10 −14 at 1 s averaging time and a linewidth below 17 Hz. This new stabilization scheme gives us the ability to transfer frequency stability in the range of 10 −15 or even better, currently accessible in the near infrared or in the visible, to mid-infrared lasers in a wide frequency range.

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We have built a frequency chain which enables to measure the absolute frequency of a laser emitting in the 28-31 THz frequency range and stabilized onto a molecular absorption line. The set-up uses an optical frequency comb and an ultrastable 1.55 µm frequency reference signal, transferred from LNE-SYRTE to LPL through an optical link. We are now progressing towards the stabilization of the mid-IR laser via the frequency comb and the extension of this technique to quantum cascade lasers. Such a development is very challenging for ultrahigh resolution molecular spectroscopy and fundamental tests of physics with molecules.I.

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