A5085191984- Astrophysics and Star Formation Studies
- Advanced Chemical Physics Studies
- Atmospheric Ozone and Climate
- Molecular Spectroscopy and Structure
- Astro and Planetary Science
- Atmospheric chemistry and aerosols
- Quantum, superfluid, helium dynamics
- Spectroscopy and Quantum Chemical Studies
- Spectroscopy and Laser Applications
- Stellar, planetary, and galactic studies
- Spacecraft and Cryogenic Technologies
- Methane Hydrates and Related Phenomena
- Catalytic Processes in Materials Science
- Mass Spectrometry Techniques and Applications
- Advanced Combustion Engine Technologies
- Scientific Research and Discoveries
- Photochemistry and Electron Transfer Studies
- nanoparticles nucleation surface interactions
- Vehicle emissions and performance
- Space Exploration and Technology
- Air Quality and Health Impacts
- Astronomical Observations and Instrumentation
- Atomic and Molecular Physics
- Radical Photochemical Reactions
- Photoreceptor and optogenetics research
Aix-Marseille Université
2013-2024
Physique des interactions ioniques et moléculaires
2014-2024
Centre National de la Recherche Scientifique
2014-2024
University of Kent
2020-2023
Laboratoire de Physique des Lasers, Atomes et Molécules
2017-2022
Université de Lille
2018-2020
Délégation Provence et Corse
2015-2019
Université de Bordeaux
2017-2019
Institut des Sciences Moléculaires
2016-2019
Délégation Normandie
2019
In the environments where stars and planets form, about one percent of mass is in form micro-meter sized particles known as dust. However small insignificant these dust grains may seem, they are responsible for production simplest (H2) to most complex (amino-acids) molecules observed our Universe. Dust recognized powerful nano-factories that produce chemical species. However, mechanism converts species on gas remains elusive. Here we report experimental evidence forming interstellar analogs...
The desorption characteristics of molecules on interstellar dust grains are important for modelling the behaviour in icy mantles and, critically, describing solid-gas interface. In this study, a series laboratory experiments exploring three small from astrophysically relevant surfaces presented. CO, O2 and CO2 at both sub-monolayer multilayer coverages was investigated non-porous water, crystalline water silicate surfaces. Experimental data modelled using Polanyi-Wigner equation to produce...
Ices are the main carriers of volatiles in protoplanetary disks and crucial to our understanding disk chemistry that ultimately sets organic composition planets. The Director’s Discretionary-Early Release Science (DD-ERS) program Ice Age on James Webb Space Telescope (JWST) follows ice evolution through all stages star planet formation. JWST’s exquisite sensitivity angular resolution uniquely enable detailed spatially resolved inventories ices disks. JWST/NIRSpec observations edge-on Class...
Abstract We present JWST MIRI MRS observations of the edge-on protoplanetary disk around young subsolar-mass star Tau 042021, acquired as part Cycle 1 GO program “Mapping Inclined Disk Astrochemical Signatures.” These data resolve mid-IR spatial distributions H 2 , revealing X-shaped emission extending to ∼200 au above midplane with a semiopening angle 35° ± 5°. do not velocity-resolve gas in spectral images, but measured is consistent magnetohydrodynamic wind origin. A collimated, bipolar...
Protostars contain icy ingredients necessary for the formation of potential habitable worlds, therefore, it is crucial to understand their chemical and physical environments. This work focused on ice features towards binary protostellar system Ced 110 IRS4A IRS4B, separated by 250 au observed with James Webb Space Telescope (JWST) as part Early Release Science (ERS) Ice Age collaboration. study aimed at exploring JWST observations IRS4B primarily unveil quantify inventories these sources....
Context. Much of the formaldehyde (H2CO) is formed from hydrogenation CO on interstellar dust grains, and released in gas phase hot core regions. Radio-astronomical observations these regions are directly related to its desorption grains.
The formation of CO2 in quiescent regions molecular clouds is not yet fully understood, despite having an abundance around 10-34 % H2O. We present a study the via non-energetic route CO + OH on non-porous H2O and amorphous silicate surfaces. Our results are form temperature-programmed desorption spectra produced two experimental routes: O2 H O3 H. maximum yield 8 with respect to starting quantity CO, suggesting barrier OH. rate reaction, based modelling results, 24 times slower than model...
Context. Water is the major component of interstellar ice mantle. In ice, chemical reactivity limited by diffusion reacting molecules, which are usually present at abundances a few percent with respect to water.
Context. It is generally agreed that hydrogenation reactions dominate chemistry on grain surfaces in cold, dense molecular cores, saturating the molecules present ice mantles. Aims. We a study of low temperature reactivity solid phase isocyanic acid (HNCO) with hydrogen atoms, aim elucidating its reaction network. Methods. Fourier transform infrared spectroscopy and mass spectrometry were employed to follow evolution pure HNCO during bombardment H atoms. Both multilayer monolayer regimes...
Abstract This roadmap article highlights recent advances, challenges and future prospects in studies of the dynamics molecules clusters gas phase. It comprises nineteen contributions by scientists with leading expertise complementary experimental theoretical techniques to probe on timescales spanning twenty order magnitudes, from attoseconds minutes beyond, for systems ranging complexity smallest (diatomic) nanoparticles. Combining some these opens up new avenues unravel hitherto unexplored...
Results of a ground-based optical monitoring campaign on 3C 390.3 in 1994-95 are presented. The broad-band fluxes (B, V, R, and I), the spectrophotometric continuum flux F(5177) integrated emission-line Ha, Hb, Hg, HeI, HeII all show nearly monotonic increase with episodes milder short-term variations superposed. amplitude increases decreasing wavelength (4400-9000 A). follow ultraviolet X-ray time delays, measured from centroids cross- correlation functions, typically around 5 days, but...
We have determined rates of leakage radioactivity from a rabbit synovial pouch in vivo for number particle systems varying sizes and differing resistance to degradation. The estimates were made using gamma scintillation camera without killing the test animals. lowest at twenty-four hours was seen with inert carbonized microspheres highest surface-labeled particles biodegradable denatured human serum albumin erythrocytes. had no adverse long-term effects on health animals' articular...
Context. Circumstellar disks and envelopes of low-mass young stellar objects (YSOs) contain significant amounts ice. Such icy material will evolve to become volatile components planetary systems, such as comets in our solar system.
HCN is a molecule central to interstellar chemistry, since it the simplest containing carbon-nitrogen bond and its solid state chemistry rich. The aim of this work was study NH3 + -> NH4+CN- thermal reaction in ice analogues. Laboratory experiments based on Fourier transform infrared spectroscopy mass spectrometry were performed characterise product formation kinetics. This purely can occur at low temperatures ices without requiring non-thermal processing by photons, electrons or cosmic...
The diffusion of molecules in interstellar ice is a fundamental phenomenon to take into account while studying the formation complex this ice. This work presents theoretical study on H2O, NH3, CO2, CO, and H2CO bulk low density amorphous (LDA) ice, taking physical conditions prevailing space, i.e. temperatures below 150 K extremely pressure. was undertaken by means molecular dynamics simulations. For CO2 for which no experimental data were available we conducted our own experiments. From...
Context. Ice-coated dust grains provide the main reservoir of volatiles that play an important role in planet formation processes and may become incorporated into planetary atmospheres. However, due to observational challenges, ice abundance distribution protoplanetary disks is not well constrained. With advent James Webb Space Telescope (JWST), we are a unique position observe these ices near- mid-infrared constrain their properties Class II disks. Aims. We present JWST Mid-InfraRed Imager...
We report on two BeppoSAX observations of BL Lac (2200+420) performed respectively in June and December 1999, as part a ToO program to monitor blazars high states activity. During both runs the source has been detected up 100 keV, but it showed quite different spectra: was concave with very hard component above 5–6 keV (; ); well fitted by single power law (). first observation an astonishing variability episode: 0.3–2 flux doubled ~ min, while 4 almost constant. This frequency–dependent...
We present near-infrared spectroscopic observations of 19 molecular clouds made using the AKARI satellite, and data reduction pipeline written to analyze those observations. The 2.5–5 μm spectra 30 objects—22 field stars behind quiescent 8 low-mass young stellar objects in cores—were successfully extracted pipeline. Those are further analyzed calculate column densities key solid phase species, including H2O, CO2, CO, OCN−. profile H2O ice band is seen vary across observed we suggest that...
To date, gas phase observations of sulphur in dense interstellar environments have only constrained the molecular carriers ∼ 1 % its predicted cosmic abundance. An additional 5 is known to be locked up solids clouds, leaving main reservoir depleted solid yet identified. Overall, OCS S-bearing molecule unambiguously detected ices thus far with infrared telescopes, although an absorption feature SO_2 has been plausibly identified at 7.5 μm. The spectral resolution and sensitivity James Webb...
To date, gas phase observations of sulphur in dense interstellar environments have only constrained the molecular carriers 1% its predicted cosmic abundance. An additional 5% is known to be locked up solids clouds, leaving main reservoir depleted solid unknown. The spectral resolution and sensitivity JWST could make a substantial difference detecting part this missing sulphur, with wavelength coverage that includes vibrational absorption features S-carriers H2S, OCS, SO2, CS2, SO, CS, S8....
(Abridged) JWST observations have measured the ice composition toward two highly-extinguished field stars in Chamaeleon I cloud. The observed extinction excess on long-wavelength side of H2O band at 3 micron has been attributed to a mixture CH3OH with ammonia hydrates, which suggests that could formed water-rich environment little CO depletion. Laboratory experiments and quantum chemical calculations suggest form via grain surface reactions CH3+OH and/or C+H2O ices. However, no dedicated...