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protonated TRP

Fragmentation of peptides


Protonated aromatic



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The main interest of the team is the to study the reactivity of small molecular clusters. The goal being to link the reactivity in gas phase to the reactivity in condensed phase. 

         Recently we are shifting to the understanding of the behavior of biological molecules in gas phase. Our main achievement was to propose a general mechanism for understanding the non radiative decay in all biological molecules.

         Each time that you body is absorbing an Ultra Violet (sun burn) photon something appends in the molecules of your body.

         What appends is what we ant to know at the basic level. In general Mother Nature has been kind enough to allow you to survive to the UV radiation! Absorbing a photon mean bringing some energy to the molecules which then might then brake. The mechanism which prevents that is call the non radiative decay : the energy initially in the molecule is very quickly (10-13 s ) dissipated in the local environment and prevent braking the chemical bond in you body.

         The mechanism we propose, that you will find in the “SDDJ” model is more general than we first imagine. It brings the energy deposited by the light rapidly in heat.

         We are at the moment trying to see what all the consequences of this model.

Moreover since we understand a bit we are trying using very fancy lasers to defeat this process. Our goal is then use lasers to break proteins in a very well controlled manner.  


We use supersonic jet to produce molecular cluster and lasers to induce chemical reactions and probe the reactions product. 

 Pages trouvées

A typical experiment is depicted above : the clusters are produced in a supersonic jet in a first vacuum chamber. they are cool down to a few Kelvin. the cluster enter the second vacuum chamber through a skimmer and pass between the two plates of a "Time of flight mass spectrometer". The first laser induces the chemical reaction and the second laser (laser sonde) delayed in time probes the reaction product by ionizing them. The ions are accelerated into the time of flight (field free region) and detected on a ion detector. The arrival time of the ion is proportional to there mass.

        *by changing the wavelength of the first laser one can see how the reaction efficiency changes with the energy.

        *by changing the delay between the first and the second laser we can monitor how fast is the reaction.