Task 1: Synthesis of solid organic compounds by microwave plasma ionization of gas.
We have developed a new system, called "Nebulotron" consisting of a high vacuum glass line in which adjustable gas mixtures can be flowed through a microwave (2.45 GHz) plasma discharge. The flown gases were mixtures of H2, CO, N2 and noble gases. We succeeded in producing solid organics. We carried out a series of analyses dedicated to investigate the molecular structure (gas chromatography-mass spectrometry, 13C-nuclear magnetic resonance spectroscopy, Fourier transformed infrared spectroscopy) and isotopic composition (NanoSIMS) of H and N in Nebulotron products (collaboration with the laboratory of Sylvie Derenne, Univ. Paris 6). We have coinjointly carried out a modeling approach in which the results were integrated in a global model of organic matter generation and transport in the nascent solar system, in collaboration with Dr. Sébastien Charnoz (IPGP) (Bekaert et al, 2018).
Task 2: Synthesis of gaseous and solid organics by photon ionization/dissociation of gas mixtures in a VUV cell coupled to the DESIRS line, Soleil synchrotron.
We are investigating the effect of photo-irradiation on the isotope composition of organic products formed in the context of the protoplanetary disk. Using the high flux of the DESIRS UV-photon line at Soleil syncrhotron, we aim at forming and trapping the organic products of the irradiation of simple gas mixtures (N2:CH4 and H2:N2:CO) to measure their chemical and isotopic compositions and compare them to extraterrestrial organic materials. Contrary to our expectation, we have been awarded only 5 days of beam time on DESIRS but have applied for additional time. We observed the formation of organic products (notably HCN and C2H2). The condensable gas products were collected on cold traps during or after the experiments for further isotope analysis. We also carried out original experiments of photo-ionization using the APSIS setup at LATMOS laboratory to provide experimental insights into pathways of photochemistry-driven molecular growth within outer Circum-Stellar Envelopes (CSE). EUV photons mimicking the interstellar UV field were generated by using a neon gas-discharge type VUV lamp coupled windowless to the photochemical APSIS reactor (Tigrine et al. 2016).
Task 3: Gas-ice interactions: fractionation of noble gases and stable isotopes.
We study the elemental and isotopic fractionation of noble gas and stable isotopes upon trapping in ice and irradiation by UV phortons. The EXCITING (Exploring Xenon in Cometary Ice by Trapping and Irradiating Noble Gases) experimental set-up built in our laboratory permits water-noble gas mixtures to be flown and adjusted using a quadrupole mass spectrometer, before being condensed onto a cold plate at around 25 K. The so-formed ice containing water and noble gases can then be heated up to any temperature and/or irradiated using a hydrogen lamp simulating interstellar radiations. Noble gases can then be released for the ice lattice upon warming, before being analyzed in static mass spectrometry. The experimental set up is connected directly to a noble gas mass spectrometer that has been upgraded as part of this project with the latest state of the art electronics. The system is operational since the beginning of 2019 and the experiments are currently under way. We developed a new stable isotope analytical system, as well as an on-line noble gas mass spectrometer to analyze directly the run products. This experiment is the only one worldwide to permit trapping and temperature-controlled desorption of volatile elements (all noble gases, nitrogen) under irradiation by UV photons. Run products can be analyzed for their abundances and isotopic ratios during these processes.
