Formation of Molecular Hydrogen in the Interstellar Medium

1. Formation of molecular hydrogen in the interstellar medium Jean Louis LEMAIRE LAMAp/LERMA Observatoire de Paris & Université de Cergy-Pontoise International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

2. Formation of molecular hydrogen in the interstellar medium International Conference on Nano-Materials and Renewable Energies It could appear at first sight that formation of molecular hydrogen in the interstellar medium (ISM) has nothing to see with the title of the conference. International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

3. They are in fact two links, even if the first of them is daring. • The first one deals with renewable energies … • but on an astronomical time scale !! • - When AGB stars become Super Novae, they expel their material out in the space and part of it (the rest is gas) constitutes the interstellar dust grains mainly made of silicates, SiC and carbonaceous material. • Much later on, when this material, coming from several such explosions, is gathered together with the pervading atomic hydrogen in giant clouds, • it starts to form a wealth of molecules (starting with the more simple H2, then promoting more complex ones … up to prebiotic ones) and • - when gravitation enters at play inside denser clumps of materials, new stars may form. • … and renewed energy will arise out of these stars ! • an ITERative process • . International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

4. Schematicdiagram * At every stages of star formation and evolution, gas and dust material are recycled back into the Interstellar Medium (ISM). * Through nucleosynthesis, + Extra-galactic infall massive stars enrich the material with heavy elements fast slow Time evolution International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

5. Planetary Nebulae International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

6. The archetype of a star forming region: OMC1 Orion Molecular Cloud International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

7. OMC1 Orion Molecular Cloud VLT ESO (UT4 + adaptive optics) False color RGB Image: M, L and K band False color RGB image (in red): 2.12 µm (K-band) H2 1-0 S(0) emission (in blue and green): Nearby continuum emission International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010 International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

8. Composition and physical/chemical state of the interstellar grains • Class Material Signatures (abs., emi.) • bare material • - Silicates Olivine (MgxFe1-x)2 SiO4 9.7 and 18 µm bands • - Graphite the more active to form H2217.5 nm bump • - Amorphous carbon and HAC7.6 µm bands • active catalyst • - PAHs 3.3, 6.2, 7.7 and 11.3 µm • - SiC 11.4 µm • - MgS 30 µm • core + ice mantle material (UV processed or not) • - Ice covered grains • CO, H2O, NH3, CH4, CO2, N2 • Methanol3.1, 4.6, 6.0, 6.85 µm • - Refractory organics covered grains3.4, 6.0 µm • Grains origin:Novae, Supernovae, ejected stellar matter International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

9. Cosmic Dust Grains: - Composed of particles which are from a few molecules to 0.1 mm in size - Solid, crystalline, porous, fluffy ….. Extremely large grains  asteroids  planetesimals Here is an ELG !! 1 km Chondrite interplanetary dust particle Porous Smooth

10. The mineral olivine (gem-quality called peridot) is a magnesium iron silicate with the formula (Mgx,Fe(1-x))2SiO4 It is one of the most common minerals on Earth, and has also been identified in meteorites, the Moon, Mars, in the dust of comet Wild 2, and within the core of comet Tempel. The ratio of magnesium and iron varies between the two endmembers of the solid solution series: Forsterite (Mg-endmember, x=1) and Fayalite (Fe-endmember, x=0). Forsterite has an unusually high melting temperature at atmospheric pressure, almost 1900°C, but the melting temperature of Fayalite is much lower (about 1200°C). The melting temperature varies smoothly between the two endmembers, as do other properties. Olivine incorporates only minor amounts of elements other than oxygen, silicon, magnesium, and iron. Manganese and nickel commonly are the additional elements present in highest concentrations. Crystal system: orthorhombic The atomic scale structure of olivine looking along the a axis. Oxygen is shown in red, silicon in pink, and magnesium/iron in blue. A projection of the unit cell is shown by the black rectangle International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

11. Silicates comprise the majority of the earth's crust, as well as most planets and moons. • Silicate compounds, including the minerals, consist of silicate anions whose charge is balanced by various cations. • - Then silicates have specific spectroscopic signatures which can be observed in space and recreated in the laboratory. International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

12. SiC While rare on Earth, silicon carbide is remarkably common in space. It is a common form of stardust found around carbon-rich stars, and examples of this stardust have been found in pristine condition in primitive (unaltered) meteorites. The silicon carbide found in space and in meteorites is almost exclusively the beta-polymorph. Analysis of SiC grains found in the Murchison carbonaceous chondrite meteorite has revealed anomalous isotopic ratios of carbon and silicon, indicating an origin from outside the solar system; 99% of these SiC grains originate around carbon-rich asymptotic giant branch stars. SiC is commonly found around these stars as deduced from their infrared spectra. International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

13. In the early stages of star formation, molecules will form: • either in the gas phase • or, for many of them, at the surface of the nano- or micro-material forming the dust grains. • The first of them is molecular hydrogen. • Numerous diagnostics & techniques are now currently used to show how such formation reactions proceed, involving: • - Atomic and molecular physics, • - Surface science • - Solid state physics • and by the more recent ones: STM techniques (at low temperature) • Theoretical works are also necessary to explain the mechanisms involved. International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

14. H2 formation on surfaces Summary The gas-grain surface interaction is the main route for the molecule formation in the ISM - Gould and Salpeter (1963) Interstellar grains acts as catalysts - from the very simple H2 formation - to the more complex chemistry The kinetics of the reaction under interstellar conditions is still not well understood - experimental aspects - what is a real interstellar grain ? - how to work in the laboratory under interstellar conditions ? Low flux (<1012 atoms/cm2/sec) and Ek(10-300 K) of H atoms Low sample temperature (5-40 K), Low background pressure (10-10 torr) - theoretical aspects what are the physical and chemical mechanisms involved ? what formalism to use to give account of them ? - Morphology - Porosity - Binding energy - Mobility - Sticking - Bare or ice covered - ……

15. H2 formation on surfaces Experimental aspects Grain surface characteristics: Atoms or molecules characteristics and interaction with the surface: * morphology (crystalline, micro- or poly- crystalline, amorphous) * role of the defects * porosity (dense / fluffy), area/unit vol. * bare grain size distribution (0.01 to 0.5 µm) * surface temperature * adsorption processes * type of interaction with the surface (physi- vs. chemi-sorption) * binding sites and energies * ice morphologies and surface coverage (ice mantles, mixtures) * flux of incoming atoms, kinetic temperature * sticking coefficient * mobility, time scales: residence time, migration time (10-12 to 10-3 s) * formation processes * recombination efficiency * desorption kinetics (thermally activated mobility?) * Ev,j & Ek International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

16. H H Formation energy partition 4.5 eV Ev,J ? Ek ? Grain heating ? Adsorption ( flux, sticking ?…) from the gas phase onto the grain T ? Composition ? Morphology ? Coverage ? H Thermal accomodation and/or sticking Desorption (residence time ?) H H Diffusion (mobility ?) Formation reaction Formation H H Desorption H Formation of H2molecules on grains Nascent H2 with internal energy H2 will cool through radiation of IR photons The molecular cloud collapse more readily Formation process  ISM dynamics (results from the balance between internal pressure and gravitational forces) Nascent H2 with large translational and small internal energy and/or grain heating Heating of the cloud Slow collapse of the molecular cloud International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

17. Surfaces, H2 formation Theoretical aspects • Reaction mechanisms • Eley-Rideal (prompt mechanism) • occur at high H atom coverage rate • creates "hot" H2 • Harris-Kasemo (hot atom mechanism) • several bounces before prompt reaction • occur at low and high H atom coverage rate • creates "hot" H2 • Langmuir-Hinshelwood • (migration mechanism by tunneling or thermal hooping) • occur at low and high H atom coverage rate •  creates H2 at surface temperature Interaction of atoms and molecules with surfaces: * physisorption (vdW interaction) * chemisorption (covalent bond) International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

18. Formation of molecular hydrogenon a silicate surfaceExperiment International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

19. "FORMOLISM"  experimental setup Atomic hydrogen source International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

20. Beam shutter: ON or OFF 0 – UHV chamber (~10-10 mbar) 1 - Substrate: - Amorphous silicate. - Temperature controlled (>5.5K). 2 – Exposure (with 1 or 2 beams) to: - molecules (MW discharge off) - atoms and molecules (MW discharge on) “FORMOLISM” experimental set up Beam 1: can be temperature controlled (20 – 300K) (MW discharge on) International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

21. QMS Simultaneous measurements during beam exposure and after exposure during the heating ramp (TPD) (Thermally Programmed Desorption) – QMS (Mass selective) in a remote location – REMPI-TOF MS Laser detection [Quantum state selective: l(v,J)] – Infrared spectroscopy RAIRS (not used in this experiment) Diagnostics International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

22. UV Laser Simultaneous measurements during beam exposure and after exposure during the heating ramp (TPD) (Thermally Programmed Desorption) – QMS (Mass selective) in a remote location – REMPI-TOF MS Laser detection [Quantum state selective: l(v,J)] The laser is tuned to the specific Q(J") [X(v",J")-EF(v',J')] transitions in order to measure the X(v",J") population – Infrared spectroscopy RAIRS (not used in this experiment) Diagnostics International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

23. micro-capillary array doser (+ translation) Quadrupole Mass Spectrometer (+ translation + rotation) Time of Flight Mass Spectrometer cold head + thermal shield (+translation) RAIRS diagnostic (KBr windows) Inside of the UHV chamber (as seen from the molecular or atomic gas beams entrance window) International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

24. Experiment scheme Diagnostics methods with state specific resolution HD+, H2+,D2+(v,J) signal H/H2 MCP D/D2 Time of flight Acceler. Extract. REMPI + Time of Flight Mass Spectrometer (TOF-MS) quantum states discrimination Excitation 2.45 GHz UV laser beam focused in front of the surface Nd:YAG laser + Dye laser 1.064µm x 2 … 600-300-200 nm Cryo generator Ts=6-150K cleaning: 800 K temperatures measurements and regulations Silicate sample Ultra High Vacuum Chamber (<10-10 mbar, n~106cm-3) pumping: primary, turbomlecular, ionic, titanium sublimation.bakingup at 150°C for ~100 hours International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

25.  Transition Q(J") International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

26. Formation of molecular hydrogenon a silicate surfaceExperimentpaper in preparation International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

27. Toward chemical complexity O2 Beam (40 % dissociation) Initially 100 O2 molecules Finally: 60 O2 and 80 O D2 Beam (60 % dissociation) Substrate: - Silicates: to be done - Water ice: Dulieu et al, A&A, 2009 Water formation H, O, N and C Interaction and Reactivity on Surfaces, in Laboratory to explain what is observed in Space International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

28. Suggested mechanisms (theoretician view) Tielens & Hagen 1982 Stantcheva et al 2002 Kaufman et al. 2005 Molecules in Space & Laboratory, Paris, May 2007, JL Lemaire

29. High Coverage Low Coverage Medium Coverage 103 x 114 Å2 Vt~800mV, It~0.15-0.2nA H on HOPG In situ observations with STMof molecular formation on graphite 171 x 155 Å2 80 x 72 Å2 International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010 Liv Hornekær, 2009, iNano Aarhus

30. H chemisorbed on HOPG Rauls Work on graphitic surfaces Chemisorption - basal plane: Jeloica & Sidis, Chem. Phys. Lett. 300, 157 (1999) Chemisorption at defects: Sha et al, Surface Science 496, 318 (2002) Sha et al, J. Am. Chem. Soc. 126, 13095 (2004) Güttler et al, Surface Science 570, 218 (2004) Chemisorbed states on graphite: Cazaux & Tielens, Astrophys. J. 604, 222 (2004)

31. Dimer formation Hornekær et al. Phys. Rev. Lett. 97, 186102 (2006)

33. In situ observations with STMof molecular formation on other surfaces(Graphene, Silicene, silicates …)studying mainly interaction and reactivity with H and O Project of collaboration between CEA, CINAM and our team International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

34. Thanks to all who have performed the work on the formation of vibrationnaly excited H2 formation S. Baouche, M. Chehrouri, H. Chaabouni, H. Mokrane E. Somson, S. Diana and G. Vidali (Syracuse University NY USA as visitingprofessor) and thank you for your attention International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

35. International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

36. Laboratoire Atomes et Molécules en Astrophysique (LAMAp) Université de Cergy-Pontoise (UCP) Website: http://www.u-cergy.fr/LERMA-LAMAP/ Head of Laboratory: JL Lemaire (jean-louis.lemaire@obspm.fr) Fundamental research: Laboratory Astrophysics Aimed at explaining how stars are forming, from the first molecules to the more evolved ones. Several fields involved: Atomic & Molecular Physics, Surface science, Chemistry, Astrophysics & Astrochemistry OMC1 (VLT-UT4-NACO) Scanning Tunneling Microscope (CERGY + CEA collaboration) "SOLEIL" synchrotron DESIRS beam-line FORMOLISM experiment at the Cergy Laboratory Laboratoire associé au LERMAUMR 8112 du CNRS Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique Observatoire de Paris + Université Pierre et Marie Curie + Université de Cergy-Pontoise + Ecole Normale supérieure + collaboration with CEA

37. PhD project: The LAMAp/LERMA group (managed by both the Observatoire de Paris and the Université de Cergy-Pontoise) opens a position for a PhD student in the project: Gas-grains interaction and reactivity forming molecules in inter- and circum-stellar conditions Starting Date: 01/02/2010 (then immediately available) Duration: 36 months Candidate: Physics, Physical chemistry or Astrophysics MSc.D. All nationalities eligible, according to the EU mobility criteria (then French nationals escepted). Funding program: European FP7-ITN 7th Framework Programme - Initial Training Networks) LASSIE (Laboratory Astrochemical Surface Science In Europe) project (PI: Prof. McCoustra Edinburgh) + ANR (Agence Nationale de la Recherche) + SESAME (CR Ile de France) contract Gross salary ~36 k€ per year. Additional travel allowance to participate in the network meetings. ResponsibleScientist: Prof. Jean Louis Lemaire (jean-louis.lemaire@obspm.fr) Theme:Laboratory astrophysics (atomic & molecular physics and surface science for astrophysics) Short description: A laboratory research project to study the reactions leading to molecular hydrogen and small molecule formation on inter- and circum-stellar dust analogues (silicates, carbonaceous materials and ices) under ultrahigh vacuum and ultralow temperature conditions. Web pages:http://www.u-cergy.fr/LERMA-LAMAP/ International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

38. PhD project: The LAMAp/LERMA group (managed by both the Observatoire de Paris and the Université de Cergy-Pontoise) opens a position for a PhD student in the project: Gas-grains interaction and reactivity forming molecules in inter- and circum-stellar conditions Project description: - Study of the atomic and molecular mechanisms as well as of the reactions pathways involved in the molecular formation within inter- and circum-stellar conditions, in the framework of gas/surface interactions and heterogeneous catalysis. - Interaction and reactivity of H, O and N (under atomic and/or molecular forms) on surfaces simulating interstellar dust grains, either dry ones (silicates or carbonaceous materials of different morphologies, material pertinent to diffuse clouds) or covered with icy mantle (water, CO …, material pertinent to dark clouds). We are in particular interested in the formation of H2, H2O, CO2… - Experiments are performed using the "FORMOLISM" experimental setup: a sample maintained at very low temperature is irradiated in an ultra high vacuum chamber by atomic and molecular beams. Three spectroscopic diagnostics are used to detect and characterize the molecular formation: 1) TPD-MS (thermally programmed desorption mass spectroscopy) to monitor the desorption kinetics of a given species (irrespective of its quantum state), using a QMS (quadrupole mass spectrometer) 2) REMPI-TOF-MS Laser spectroscopy (resonantly enhanced multiphoton ionization associated with time of flight mass spectroscopy) allowing rovibrational quantum states discrimination. This diagnostic is mainly used for H2 formation studies. 3) RAIRS (reflection absorption infrared spectroscopy) is implemented to diagnose both the ice structure and the molecules formed on the surface as well as their physical/chemical evolution during TPD heating. 4) STM in the near future for in situ formation observations. - The main aim of the project is to provide fundamental data and information on gas/surface interactions necessary to the modeling of astrophysical environments. Such models are designed to interpret astronomical and radio astronomical observations (Spitzer, Herschel, ALMA). Scientific environment: Responsible Scientist: Prof. Jean Louis Lemaire (jean-louis.lemaire@obspm.fr) An active collaboration exists between our research team and V Pirronello (Catania) and G Vidali (Syracuse USA). Theoretical aspects of gas interactions with model surfaces are treated by both the LCAM (Orsay) and the LERMA (Meudon) theoretician groups. International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

39. International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

40. Study and importance Cosmic dust was once solely an annoyance to astronomers, as it obscures objects they wish to observe. When infrared astronomy began, those previously annoying dust particles were observed to be significant and vital components of astrophysical processes. For example, cosmic dust can drive the mass loss when a star is nearing the end of its life, play a part in the early stages of star formation, and form planets. In our own solar system, dust plays a major role in the zodiacal light, Saturn's B Ringspokes, the outer diffuse planetary rings at Jupiter, Saturn, Uranus and Neptune, and comets. The study of dust is a many-faceted research topic that brings together different scientific fields: physics (solid-state, electromagnetic theory, surface physics, statistical physics, thermal physics), fractal mathematics, chemistry (chemical reactions on grain surfaces), meteoritics, as well as every branch of astronomy and astrophysics.[1] These disparate research areas can be linked by the following theme: the cosmic dust particles evolve cyclically; chemically, physically and dynamically. The evolution of dust traces out paths in which the universe recycles material, in processes analogous to the daily recycling steps with which many people are familiar: production, storage, processing, collection, consumption, and discarding. Observations and measurements of cosmic dust in different regions provide an important insight into the universe's recycling processes; in the clouds of the diffuse interstellar medium, in molecular clouds, in the circumstellar dust of young stellar objects, and in planetary systems such as our own solar system, where astronomers consider dust as in its most recycled state. The astronomers accumulate observational ‘snapshots’ of dust at different stages of its life and, over time, form a more complete movie of the universe's complicated recycling steps. The detection of cosmic dust points to another facet of cosmic dust research: dust acting as photons. Once cosmic dust is detected, the scientific problem to be solved is an inverse problem to determine what processes brought that encoded photon-like object (dust) to the detector. Parameters such as the particle's initial motion, material properties, intervening plasma and magnetic field determined the dust particle's arrival at the dust detector. Slightly changing any of these parameters can give significantly different dust dynamical behavior. Therefore one can learn about where that object came from, and what is (in) the intervening medium. Some bulk properties of cosmic dust Cosmic dust is made of dust grains and aggregates of dust grains. These particles are irregularly-shaped with porosity ranging from fluffy to compact. The composition, size, and other properties depends on where the dust is found, and conversely, a compositional analysis of a dust particle can reveal much about the dust particle's origin. General diffuse interstellar medium dust, dust grains in dense clouds, planetary rings dust, and circumstellar dust, are each different in their characteristics. For example, grains in dense clouds have acquired a mantle of ice and on average are larger than dust particles in the diffuse interstellar medium. Interplanetary dust particles (IDPs) are generally larger still. In circumstellar dust, astronomers have found molecular signatures of CO, silicon carbide, amorphous silicate, polycyclic aromatic hydrocarbons, water ice, and polyformaldehyde, among others. (In the diffuse interstellar medium, there is evidence for silicate and carbon grains.) Cometary dust is generally different (with overlap) from asteroidal dust. Asteroidal dust resembles carbonaceous chondritic meteorites, and cometary dust resembles interstellar grains, which can include the elements: silicates, polycyclic aromatic hydrocarbons, and water ice. Dust grain formation The large grains start with the silicate particles forming in the atmospheres of cool stars, and carbon grains in the atmospheres of cool carbon stars. Stars that have evolved off the main sequence and have entered the giant phase of their evolution are a major source of dust grains in galaxies. Star dust, sung and written in the popular media, is a colloquial term referring to the birthplace of most dust grains in the Universe. If one indeed traces the origin of the elements out of which human bodies are made, they are star dust. Astronomers know that the dust is formed in the envelopes of late-evolved stars from specific observational signatures. An (infrared) 9.7 micrometre emission silicate signature is observed for cool evolved (oxygen-rich giant) stars. And an (infrared) 11.5 micrometre emission silicon carbide signature is observed for cool evolved (carbon-rich giant) stars. These help provide evidence that the small silicate particles in space came from the outer envelopes (ejecta) of these stars. It is believed that conditions in interstellar space are generally not suitable for the formation of silicate cores. The arguments are that: given an observed typical grain diameter a, the time for a grain to attain a, and given the temperature of interstellar gas, it would take considerably longer than the age of the universe for interstellar grains to form. Furthermore, grains are seen to form in the vicinity of nearby stars in real-time, meaning in a) nova and supernova ejecta, and b) R Coronae Borealis, which seem to eject discrete clouds containing both gas and dust. Most dust in our solar system is highly processed dust, recycled from the material out of which our solar system formed and subsequently collected in the planetesimals, and leftover solid material (for example: comets and asteroids), and reformed in each of those bodies' collisional lifetimes. During our solar system's formation history, the most abundant element was (and still is) H2. The metallic elements: magnesium, silicon, and iron, which are the principal ingredients of rocky planets, condensed into solids at the highest temperatures. The range of elements of the solar nebula between H2 and (Mg, Si, Fe) is not known well (Wood, J., 1999). Some molecules such as CO, N2, NH3, and free oxygen, existed in a gas phase. Some molecules, for example, graphite (C) and SiC condensed into solid grains. Some molecules also formed complex organic compounds and some molecules formed frozen ice mantles, of which either could coat the "refractory" (Mg, Si, Fe) grain cores. The formation of these molecules was determined, in large part, by the temperature of the solar nebula. Since the temperature of the solar nebula decreased with heliocentric distance, scientists can infer a dust grain's origin(s) with knowledge of the grain's materials. Some materials could only have been formed at high temperatures, while other grain materials could only have been formed at much lower temperatures. The materials in a single interplanetary dust particle often show that the grain elements formed in different locations and at different times in the solar nebula. Most of the matter present in the original solar nebula has since disappeared; drawn into the Sun, expelled into interstellar space, or reprocessed, for example, as part of the planets, asteroids or comets. International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

41. Interstellar Grain Material H2 (HD, D2) Formation H2 (HD, D2) desorption Physisorption Polycristalline silicates Pirronello et al. 1997 (telluric olivine) Amorphous carbon Pirronello et al. 1999 Amorphous water ice Manico et al. 2001 Roser et al. 2002, 2003 Hornekaer et al. 2003 Hornekaer et al. 2005 Perets et al. 2005, 2007 Amiaud et al. 2007 Dulieu et al. 2005 Amiaud et al. 2006, 2008 Amorphous silicates (Fex, Mg1-x)2SiO4, x=0.5 Vidali et al. 2007 0<x<1 Vidali et al. (submitted) Graphite Creighan et al. 2006 Islam et al. 2007 Latimer et al. 2008 Chemisorption Graphite Zecho et al. 2002, 2003, 2004 Hornekaer et al. 2006 Güttler et al. 2004

42. Techniques of surface science (Woodruff & Delchar 1994) Revue de Projet JLL – 22/11/2007

43. Zecho et al. 2002 H2 formation on dust grains under PDR and post-shock conditions HD TPD signal

44. Position de l'équipe dans la concurrence internationale Travaux expérimentaux sur la formation de H2 (HD, D2) physisorbé chimisorbé Waterloo team (Govers T., Ca) 1980 Bolométrie Cinétique de physisorption, H2 et D2 N'est plus en activité Syracuse + Catania team (Vidali G. , USA + Pirronello V., It) 1997 TPD Silicates (Olivine), carbone amorphe, glace d'eau, de CO et de CO2 Formation de HD V. Pirronello: Collaboration très active avec Cergy UC London team (Price S., UK) 1999 REMPI-TOF Graphite (15K) Formation de H2 et HD, diagnostic (v,j) Bayreuth team (Zecho T., Küppers J., G) 2002 TPD, ELS, HREELS HOPGraphite 2006STM Formation de H2 et D2 Odense team (Baurichter A. & Hornekaer L., Dk) 2003 TPD Glace d'eau Formation de HD, désorption de D2 HOPGraphite, Ek(q) de H2 (D2) 2006 LAAD Activité arrêtée, déplacée à Aarhus (Cf. infra) Postdoc=notre 1er doc. Observatoire de Paris & Cergy-Pontoise team (Lemaire JL, Fr) 2005 TPD, REMPI-TOF, 2009 RAIRS & … STM 200x Formation de molécules simples et complexes sur des glaces d'eau Formation de D2, désorption H2, HD, D2 et de mélanges, énergies d'adsorption, diagnostic (v,j), ortho/para Aarhus team (Hornekaer L. & Besenbacher F., Dk) 2006 STM HOPGraphite, in situ formation de D2 Postdoc=notre 1er doc. Retour ?

45. Cosmic dust was once solely an annoyance to astronomers, as it obscures objects they wish to observe. When infrared astronomy began, those previously annoying dust particles were observed to be significant and vital components of astrophysical processes. For example, cosmic dust can drive the mass loss when a star is nearing the end of its life, play a part in the early stages of star formation, and form planets. In our own solar system, dust plays a major role in the zodiacal light, Saturn's B Ringspokes, the outer diffuse planetary rings at Jupiter, Saturn, Uranus and Neptune, and comets. The study of dust is a many-faceted research topic that brings together different scientific fields: physics (solid-state, electromagnetic theory, surface physics, statistical physics, thermal physics), fractal mathematics, chemistry (chemical reactions on grain surfaces), meteoritics, as well as every branch of astronomy and astrophysics.[1] These disparate research areas can be linked by the following theme: the cosmic dust particles evolve cyclically; chemically, physically and dynamically. The evolution of dust traces out paths in which the universe recycles material, in processes analogous to the daily recycling steps with which many people are familiar: production, storage, processing, collection, consumption, and discarding. Observations and measurements of cosmic dust in different regions provide an important insight into the universe's recycling processes; in the clouds of the diffuse interstellar medium, in molecular clouds, in the circumstellar dust of young stellar objects, and in planetary systems such as our own solar system, where astronomers consider dust as in its most recycled state. The astronomers accumulate observational ‘snapshots’ of dust at different stages of its life and, over time, form a more complete movie of the universe's complicated recycling steps. The detection of cosmic dust points to another facet of cosmic dust research: dust acting as photons. Once cosmic dust is detected, the scientific problem to be solved is an inverse problem to determine what processes brought that encoded photon-like object (dust) to the detector. Parameters such as the particle's initial motion, material properties, intervening plasma and magnetic field determined the dust particle's arrival at the dust detector. Slightly changing any of these parameters can give significantly different dust dynamical behavior. Therefore one can learn about where that object came from, and what is (in) the intervening medium. International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

46. Cosmic dust is a type of dust composed of particles in space which are from a few molecules to 0.1 mm in size Cosmic dust can be further distinguished by its astronomical location: intergalactic dust, interstellar dust, interplanetary dust (such as in the zodiacal cloud) and circumplanetary dust (such as in a planetary ring). In our own Solar System, causes the zodiacal light. Sources include: comet dust, asteroidal dust, dust from the Kuiper belt, and interstellar dust passing through our solar system. The terminology has no specific application for describing materials found on the planet Earth, other than in the most general sense that all elements with an atomic mass higher than hydrogen are believed to be formed in the core of stars via stellar nucleosynthesis and supernova nucleosynthesis events. As such all elements that exist can be indiscriminately considered to be a form of "cosmic dust". International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

47. Cosmic dust of the Andromeda Galaxy as revealed in infrared light by Infrared Space Telescope (Spitzer, Herschel) Cosmic dust of the Horsehead Nebula as revealed by the Hubble Space Telescope (HST) - The structural properties of cosmic dust has been improved by observations at higher spectral resolution and in a wider range of wavelengths. - However, the formation and processing of main dust components in different astrophysical environments is not yet completely understood. - Spectroscopy is a main tool to characterize dust analog materials and to monitor ongoing structural transformations and provides also the major link to astronomical observations and the tool for identification of cosmic dust properties. - There is a lot of laboratory work to re-create cosmic dust analogs and to study thermal, UV and ion irradiation processing in order to understand cosmic dust formation and processing in space. International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

48. A silicate is a compound containing a silicon bearing anion. The great majority of silicates are oxides Silicates comprise the majority of the earth's crust, as well as most planets and moons. Sand, Portland cement, and thousands of minerals are examples of silicates. Silicate compounds, including the minerals, consist of silicate anions whose charge is balanced by various cations. Myriad silicate anions can exist, and each can form compounds with many different cations. Mineralogically, silicate minerals are divided according to structure of their silicate anion into the following groups: Nesosilicates (lone tetrahedron) - [SiO4]4−, eg olivine. Sorosilicates (double tetrahedra) - [Si2O7]6−, eg epidote, melilite group. Cyclosilicates (rings) - [SinO3n] 2n−, eg tourmaline group. Inosilicates (single chain) - [SinO3n] 2n-, eg pyroxene group. Inosilicates(double chain) - [Si4nO11n] 6n−, eg amphibole group. Phyllosilicates (sheets) - [Si2nO5n] 6n−, eg micas and clays. Tectosilicates (3D framework) - [AlxSiyO2(x+y)] x−, eg quartz, feldspars, zeolites. International Conference on Nano-Materials and Renewable Energies (ICNMRE) Safi (Morocco) July 2010

49. MC