A5004691111- Mass Spectrometry Techniques and Applications
- Analytical Chemistry and Chromatography
- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
- Molecular spectroscopy and chirality
- Molecular Spectroscopy and Structure
- Photochemistry and Electron Transfer Studies
- Chemical Synthesis and Analysis
- Various Chemistry Research Topics
- Atomic and Molecular Physics
- Crystallography and molecular interactions
- Photoreceptor and optogenetics research
- Protein Structure and Dynamics
- Spectroscopy and Laser Applications
- Atmospheric Ozone and Climate
- Catalytic Processes in Materials Science
- Chemical Reactions and Isotopes
- Ion-surface interactions and analysis
- Renal function and acid-base balance
- DNA and Nucleic Acid Chemistry
- Inorganic Fluorides and Related Compounds
- Radioactive contamination and transfer
- Atomic and Subatomic Physics Research
- Organic Chemistry Cycloaddition Reactions
- Thermodynamic properties of mixtures
Institut des Sciences Moléculaires d'Orsay
2012-2024
Université Paris-Saclay
2006-2024
Centre National de la Recherche Scientifique
2009-2024
Institut des Sciences Moléculaires
2024
Université Paris-Sud
2005-2022
Centre Hospitalier d'Orsay
2015-2019
Institut de Chimie Moléculaire et des Matériaux d'Orsay
2013
Laboratoire de Chimie Physique
2010-2013
École Polytechnique Fédérale de Lausanne
2010
Université Claude Bernard Lyon 1
2010
Vibrational spectroscopy in supersonic jet expansions is a powerful tool to assess molecular aggregates close ideal conditions for the benchmarking of quantum chemical approaches. The low temperatures achieved as well absence environment effects allow direct comparison between computed and experimental spectra. This provides potential data which can be revisited hone different computational techniques, it allows critical analysis procedures under setting blind challenge. In latter case,...
Laser-desorbed quinine and quinidine have been studied in the gas phase by combining supersonic expansion with laser spectroscopy, namely, laser-induced fluorescence (LIF), resonance-enhanced multiphoton ionization (REMPI), IR-UV double resonance experiments. Density funtional theory (DFT) calculations done conjunction experimental work. The first electronic transition of is π-π* nature, molecules weakly fluoresce phase, contrast to what was observed solution (Qin, W. W.; et al. J. Phys....
The photofragmentation of protonated tryptophan has been investigated in a unique experimental setup, which ion and neutral issued from the are detected coincidence, time position. From these data extracted kinetic energy, number fragments associated with an ion, their masses, order fragmentation steps. Moreover, scale ranging tens nanoseconds to milliseconds is obtained. all data, comprehensive mechanism proposed.
The conformation of model [Arg(Ala)4X(Ala)4Lys+2H]2+ and [Arg(Gly)4X(Gly)4Lys+2H]2+ peptides has been systematically investigated as a function the central amino acid X through combined experimental theoretical approach. Mass spectrometry-based ion mobility measurements have performed together with conformational sampling using replica-exchange molecular dynamics to probe influence each on stable peptide conformation. Satisfactory agreement is obtained between measured calculated diffusion...
Abstract Conformational flexibility and chirality both play a key role in molecular recognition. It is therefore very useful to develop spectroscopic methods that simultaneously probe properties. has been theoretically predicted photoelectron circular dichroism (PECD) should be sensitive conformational isomerism. However, experimental proof less forthcoming only exists for few favorable cases. Here, we present new PECD scheme based on resonance‐enhanced two‐photon ionization (RE2PI) using...
Chiral recognition in protonated cinchona alkaloid dimers has been studied mass spectrometry experiments. The experimental setups involved a modified 7T FT-ICR (Fourier transform-ion cyclotron resonance) spectrometer (MS) and Paul ion trap both equipped with an electrospray ionization source (ESI). coupled to frequency-doubled dye laser. fragmentation of made from cinchonidine (Cd) the two pseudoenantiomers quinine, namely, quinine (Qn) quinidine (Qd), assessed by means collision-induced...
Ion mobility experiments are combined with Infra-Red Multiple Photon Dissociation (IRMPD) spectroscopy and quantum chemical calculations for assessing the role of chirality in structure protonated sodiated di- or tetra-peptides. Sodiated systems show a strong dependence competition between Na(+)O Na(+)π interactions. Chirality effects more subtle manifest themselves by differences secondary interactions such hydrogen bonds neutral groups those involving aromatic rings.
Chirality plays a fundamental role in the molecular recognition processes. Molecular flexibility is also crucial recognition, allowing interacting molecules to adjust their structures and hence optimize interaction. Methods probing simultaneously chirality conformation are therefore crucially needed. Taking advantage of possible control gas phase conformational distribution between equatorial axial conformers resulting from ring inversion jet-cooled 1-indanol, we demonstrate here sensitivity...
The excited state dynamics of protonated tryptophan–leucine ions WLH+, generated in an electrospray source, is investigated by photo-induced fragmentation the gas phase, using femtosecond laser pulses. Two main features arise from experiment. Firstly, initially ππ* decays very quickly with 2 time constants 1 and 10 ps. Secondly, transient signals recorded on different fragments are not same which indicates two competing primary processes. One involves a direct dissociation that gives...
The structural modifications of (S)-1,2,3,4-tetrahydro-3-isoquinoline methanol (THIQM) upon ionisation have been investigated in jet-cooled conditions, by means laser-induced fluorescence, REMPI, and IR-UV ion-dip spectroscopy the neutral ground state ion. These results combined with ab initio calculations, support presence jet two low-energy conformers THIQM. In most stable Conformer I, CH2OH substituent acts as a hydrogen bond donor to nitrogen lone pair equatorial position. this case,...
New information on the photo-fragmentation of biomolecules is obtained from detection neutral and ionic fragments using a time position resolved coincidence technique that reveals whether an photofragment associated with one or more fragments. In case sequential dissociation, both fragmentation channels are identified as well their ordering.
Changing the chirality of one residue prevents formation an OH⋯O intramolecular hydrogen bond in cyclo di-tyrosine.
The conformational landscape of the diketopiperazine (DKP) dipeptide built on tyrosine and proline, namely, cyclo Tyr-Pro, is studied by combining resonance-enhanced multiphoton ionization, double resonance infrared ultraviolet (IR-UV) spectroscopy, quantum chemical calculations. Despite geometrical constraints due two aliphatic rings, DKP Tyr-Pro a flexible molecule. For both diastereoisomers, LTyr-LPro LTyr-DPro, structural families coexist under supersonic jet conditions. In most stable...
Abstract The gas‐phase structures of the cinchona alkaloids, hydroquinine and its pseudoenantiomer hydroquinidine, are studied in a supersonic expansion by means laser‐induced fluorescence IR/UV double‐resonance spectroscopy. Vibrational spectroscopy combined with density functional calculations show that conformational properties two pseudoenantiomers identical. In both cases, they exist isoenergetic forms, similar IR spectra. Both conformers to most stable cis ‐γ‐open form quinine; differ...
Protonated cinchona alkaloids and their dimers undergo photochemical reaction in the gas phase, leading to UV-specific photofragments, not observed by collision-induced dissociation. Simultaneous coupling of UV IR lasers with a Paul ion trap has been achieved for obtaining vibrational spectrum fragments arising from photodissociation. The structure photoproduced radical fully characterized comparing experimental that simulated DFT calculations.
Intramolecular charge-transfer reaction in chiral (S) 1,2,3,4-tetrahydro-3-isoquinoline methanol (THIQM) has been investigated the condensed phase and jet-cooled conditions by means of laser-induced fluorescence, dispersed emission, resonance-enhanced two-photon ionization, IR-UV double resonance experiments, as well quantum chemical calculations. In phase, THIQM only shows local emission nonpolar protic solvents dual aprotic polar solvents, where solvent-polarity dependent Stokes shifted is...
We have developed a fast multihit position and time sensitive detector with zero dead-time for heavy particles in the keV energy range. This new type of makes use micro-channel plates (MCP) assembly combines detection based on delay line anode simultaneous particle imaging CCD-camera. The pickup accuracy is enhanced by digitalizing MCP biasing signal. detector, operating at kHz repetition rate, allows resolution better than 100μm 100ps to be achieved.
Abstract An achiral chromophore can acquire a chiral spectroscopic signature when interacting with environment. This so-called induced chirality is documented in electronic or vibrational circular dichroism, which arises from the coupling between electric and magnetic transition dipoles. Here, we demonstrate that chiroptical response also within dipole approximation by observing asymmetric scattering of photoelectron ejected an interaction host. In phenol–methyloxirane complex, removing...
The photofragmentation dynamics of Ar2+ and Ar3+ clusters has been investigated at a 527 nm wavelength (2.35 eV) using setup that allows simultaneous detection the ionic neutral fragments in coincidence experiment. Measurement positions times flight enables principle complete description fragmentation dynamics. is similar to with, addition, ejection third fragment can be or ionized via resonant electron capture. This attributed triangular geometry ion.
Photo-fragmentation of protonated alkaloids results in C<sub>8</sub>–C<sub>9</sub> cleavage accompanied or not by hydrogen migration, with a stereochemistry-dependent branching ratio.
Ar2(+) ions produced in a cooled supersonic expansion by electron-impact ionization are accelerated at 2.5 keV and kept during few milliseconds inside linear electrostatic trap. The lifetime of the metastable ion is determined from measurement rate argon atoms escaping relative populations measured as function pressure temperature expansion, i.e., mean cluster size. Possible mechanisms responsible for formation discussed.