1. Europlanet Strategic Workshop I3 (Integrated Infrastructure Initiative) on Planetology (in FP7) ESA/ESTEC, The Netherlands, 26-27 February 2007 Laboratory studies of gas-phase neutral reactions of planetary relevance using the “Crossed Molecular Beams” scattering technique with mass spectrometric detection and also LIF (Laser-Induced-Fluorescence) and REMPI (Resonance-Enhanced-Multi-Photon-Ionization) Casavecchia P., Balucani N., Leonori F., Petrucci R., Volpi G. G. Dipartimento di Chimica, Università degli Studi di Perugia 06123 Perugia, Italy

2. To be included in a model a reaction must be:  thermodynamically feasible  relatively fast (small activation energy)  of known branching ratios of products What can a reaction dynamics study tell us about neutral reactions which are relevant in planetary atmospheres? reaction kinetic studies provide us with the rate constants, but are rarely able to determine the reaction products the experimental investigation of the elementary processes at the microscopic level provides us with the most detailed knowledge of gas-phase reactions and aims to verify whether a specific reaction pathway is accessible by the system

3. Reaction Dynamics  elementary processes under single collision conditions crossed molecular beams  the colliding species are confined in distinct beams which cross each other at a specific angle and collision energy  the species of each beam are made to collide only with the molecules of the other beam and the formed products fly undisturbed towards the detector  this allows us to observe the consequences of a single molecular collision, preventing secondary collisions and wall effects atomic beam source molecular beam source detector  crossed molecular beams + mass spectrometric detection P < 10 -5 Pa

4. primary beam source Crossed beam method + "universal" mass spectrometric detection and time-of-flight analysis Perugia secondary beam source tunable electron impact ionizer - crossing angle: 90° (45°, 135°) - continuous beams

7. TOF spectra at LAB angle  =34° (17 eV electron energy) By using soft EI in a CMB experiment at E c =54.0 kJ/mol we have been able to unambiguously detect the following radical and molecular products: 7 CH 2 CHO (vinoxy) CH 3 CO (acetyl) CH 2 CO (ketene) CH 3 (methyl) CH 2 (methylene) CH 3 + HCO 43% (major channel) CH 2 CHO + H 27% CH 2 CO + H 2 13% (1st time established) CH 3 CO + H 1% (1st time observed) CH 2 + HCHO 16% J. Phys. Chem. A (2005) Branching Ratios: The reaction O( 3 P)+C 2 H 4

8. The reactions N( 2 D)+CH 4 N( 2 D)+C 2 H 2 N( 2 D)+C 2 H 4 N( 2 D)+H 2 O N( 2 D)+H 2 Laboratory studies on N( 2 D) reactions of relevance to the chemistry of planetary atmospheres (Titan) A suite of N-bearing organic molecules: HCCN, CH 2 NH, CH 3 CN, CH 2 CHN, HNO, NH, have been identified as products Vuitton et al. ApJ (2006) “Critical review of N*, N +, N 2 +, N 2 ++ production and loss processes of relevance to Titan’s atmosphere” in collaboration with O. Dutuit et al., Planetary and Space Science (in preparation)

9. Laboratory studies on the dynamics of neutral-neutral gas-phase reactions of O, N, C atoms and OH, CN and C 2 radicals with inorganic and organic molecules of relevance in planetary atmospheres and prebiotic chemistry

10. Our laboratory activity can fit into the following categories: ●JRA (Joint Research Activities) with other teams (e.g., Rennes, Orsay, Grenoble, Trento, Basel, ……) tackling in a synergistic way the kinetics/dynamics/spectroscopy of gas-phase chemical processes relevant to planetary atmospheres ●TNA (Trans-National-Access) within Task and sub-Tasks in - in Missions support / development (Spectrometry, Astrobiology) - in Observation / Measurements (Laboratory data for modelling theatmospheres of Planets) ● NA (Networking activities)