europlanet strategic workshop i3 (integrated infrastructure initiative) on planetology (in fp7)...
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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
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
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
primary beam
source
Crossed beam method + "universal" mass spectrometric
detection and time-of-flight analysisPerugia
secondary beam source
tunable electron impact ionizer
- crossing angle: 90° (45°, 135°)- continuous beams
TOF spectra at LAB angle =34°
(17 eV electron energy) By using soft EI in a CMB experiment at Ec=54.0
kJ/mol we have been able to unambiguously detect the following radical and molecular products:7 CH2CHO (vinoxy) CH3CO (acetyl) CH2CO (ketene) CH3 (methyl)
CH2 (methylene)
CH3 + HCO 43% (major channel)
CH2CHO + H 27%
CH2CO + H2 13% (1st time established)
CH3CO + H 1% (1st time observed)
CH2 + HCHO 16%
J. Phys. Chem. A (2005)
Branching Ratios:
The reaction O(The reaction O(33P)+CP)+C22HH44
The reactions N(2D)+CH4
N(2D)+C2H2
N(2D)+C2H4
N(2D)+H2O
N(2D)+H2
Laboratory studies on N(2D) reactions of relevance to the
chemistry of planetary atmospheres
(Titan)A suite of N-bearing organic molecules: HCCN, CH2NH, CH3CN, CH2CHN, HNO, NH, have been identified as products
Vuitton et al.ApJ (2006)
“Critical review of N*, N+, N2+, N2
++ production and loss processes of relevance to Titan’s atmosphere”
in collaboration with O. Dutuit et al.,
Planetary and Space Science (in preparation)
Laboratory studies on the dynamics of neutral-neutral
gas-phase reactions of O, N, C atoms and OH, CN and C2
radicals with inorganic and organic molecules of relevance in planetary atmospheres and
prebiotic chemistry
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 the atmospheres of Planets)
● NA (Networking activities)