Service de Chimie Quantique et Photophysique
(Atomes, Molécules et Atmosphères)
Laboratoire Européen Associé – European Associated Laboratory

Chimie Physique Moléculaire Expérimentale

(Experimental Molecular Chemical Physics)

Main theme: High-resolution experimental molecular spectroscopy applied to chemical reactivity and the chemistry of the atmosphere.

Research themes

Vibration-rotation modeling : astrophysical and dynamical applications

The vibration-rotation structure of polyatomic species is investigated up to highly excited ranges, with special emphasis on acetylene. Polyad or vibrational clusters are built including rotational structure, to reproduce all known literature data within typical high resolution instrumental accuracy. Partition functions are being calculated accounting for nuclear spin statistics. Intramolecular vibrational redistribution is theoretically modeled. Home-made experimental developments are stimulated.

Absorption line profiles and cross sections

Measurements of absorption line parameters (positions, absolute intensities, widths) and cross sections using Fourier transform spectroscopy, with state-of-the-art accuracy. Specific measurements are performed on reactive compounds and/or species in chemical equilibrium with others, in spectral regions matching the infrared atmospheric windows.

Molecular agregates and prebiotic molecules

Supersonic jet-cooled molecules are probed at high resolution in the IR and NIR spectral ranges using a variety of instrumental techniques, including near infrared CW-CRDS and Femto-FT-CEAS, with emphasis on small and larger molecular aggregates, and on larger species. Nuclear spin isomerisation processes also motivate some of the experiments.

Reference spectroscopic data

Absorption line parameters (positions, absolute intensities and widths) and cross sections of molecules measured in the laboratory in the mid-infrared, near-infrared, visible and ultraviolet ranges (600 – 40000 cm-1) are compiled and provided to the scientific community.

Technological development

In addition to a variety of instrumental developments around conventional FTIR spectroscopic techniques, there is a specific effort towards the coupling of optical probes to investigate jet-cooled molecules and aggregates. Femto-FT-CEAS is under development, in particular, merging FTIR, femto comb and high finesse cavity in a single experiment.

Software development

We write software to (i) treat high resolution spectra allowing to measure line profiles parameters including instrumental contribution of lasers or interferometers, and (ii) analyze spectral structures, such as those of asymmetric rotors and linear molecules.

Spectral analysis and model-Hamiltonians

High resolution spectra of di- and poly-atomic molecules recorded in various spectral ranges are analysed. In this framework, we contribute to the theoretical development of model-Hamiltonians (rotation-vibration-torsion) and computer codes allowing their resolution.