Permanent staff : Claudine Crépin-Gilbert (group leader), Didier Chamma, Michèle Chevalier, Wutharath Chin

PhD students : Alejandro Gutierrez Quintanilla (to be coming), Rolando Lozada-Garcia (former), Raphaël Thon (former)

Group picture

Research activities

Dynamics and molecular spectroscopy in cryogenic solids

Our research activities focus on the influence of the environment surrounding a molecular system. To better understand, examine and exploit such effect on fundamental molecular processes (e.g. electronic or vibrational relaxation, reactivity, etc.), the systems are investigated in cryogenic matrices. Such low temperature (4-40 K) and inert media (rare gases, nitrogen, parahydrogen) allow for a simpler spectroscopy compared to condensed phase.

In our studies, the environment consists of the medium, i.e. the matrix whereby the molecular system is being trapped but also the surrounding molecules since one can easily control the concentration, thereby ranging from conditions of isolated molecules to aggregates. Another big advantage of matrix isolation spectroscopy lies in the formation of unstable molecules such as intermediate species or radicals, which are difficult to access in the gas phase.

Topics

 
 Photoreactivity : isomerisation, fragmentation in inert matrices as induced by IR or UV/visible laser excitation.

 Vibrational dynamics : The vibrational relaxation is followed by IR degenerate four-wave mixing experiments at the picoseconde and femtoseconde timescales. This gives access to the vibrational decoherence.

Our research activities are two-fold : experimental and theoretical.

Experiments

• Cryogenic methods : studies of molecules in inert gas matrices (N2, Ne, Ar, Xe…)
• Experiments in solid parahydrogen.
• Analysis by electronic (emission, absorption) and vibrational (Fourier-transform IR) spectroscopy

Theory

Experimental data are interpreted in the light of quantum chemical calculations (ab initio methods and density functional theory DFT) : electronic structures and frequencies.

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Systems of interest : molecules and hydrogen-bonded systems of biological interest, species of atmospherical (carbonyl compounds) and astrophysical (cyanopolyynes) interest.

 Molecules of biological interest

• Small organic molecules possessing H-bonds : small carbohydrates, acetylacetone ;
• Amino acids and small peptides ;
• Tetrapyrrolic molecules : Porphyrine and phthalocyanine

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 Atmospherical interest

• Carbonyl compounds : glycolaldehyde

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 Astrophysical interest : cyanopolyynes HCnN