LASER EVAPORATION OF BIOMOLECULES FROM MICRO LIQUID JET UNDER VACUUM

Work package:
Gas-phase laser spectroscopy can determine the structure of complex molecules and their hydrated aggregates containing a limited and controlled number of water molecules. Our team has demonstrated its expertise in this area by developing an experimental setup dedicated to the study of “micro-hydrated” biomolecular complexes—an experimental challenge. In this setup, the molecules are deposited onto a solid graphite substrate and then evaporated by laser irradiation of the sample. They are subsequently coupled to a supersonic gas expansion where collisions with water molecules stabilize the micro-hydrated aggregates. This method has demonstrated the validity of the spectroscopic approach and highlighted the role of a few water molecules—known as “structural” water molecules—in stabilizing certain conformations. These structural water molecules are not solvent molecules in the macroscopic sense. They are extracted from the solvent to interact directly and locally with the molecule, thereby strongly influencing its structure. Until now, it has never been possible to systematically stabilize aggregates with enough water molecules to study the role of the solvent using spectroscopy. Furthermore, the initial conditions of the molecules (in solid form, deposited on a graphite sample) are not realistic for biomolecules that function. This are major obstacles that we are seeking to overcome with this project where the molecules will be evaporated from a liquid micro jet, with a resonant infrared laser so that they can be extracted into vacuum with a sufficient amount of water molecules to represent a solvation shell of the system. The internship will consist in improving the prototype that we have already built and that has proved the feasibility of the concept and use it for the first experiments. The work will be instrumental and experimental and can be adapted to student with background in physics and chemistry. The internship could be followed by a PhD project, depending on funding opportunities.