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Institut des Sciences Moléculaires d'Orsay


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samedi 7 décembre


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Accueil > Équipes scientifiques > Systèmes Moléculaires, Astrophysique et Environnement (SYSTEMAE) > Offres de stages, thèses et post-docs > Cosmic dust energetic processing : an efficient molecule factory ?

Stage de M2

Cosmic dust energetic processing : an efficient molecule factory ?

Niveau M2 ou thèse

Cosmic organic materials, from dust to gas phase molecules, originate in the envelopes of cool late type stars, pass through the interstellar medium, enter in molecular clouds where collapse of the clouds leads to primitive nebulae and eventually to the formation of protoplanetary disks. During each of these phases, modifications of the matter are strongly influenced by UV light and Galactic cosmic rays swift ions irradiations. Moreover, these may provide the missing link between dust and molecules in interstellar space. When incorporated in the first solids of the protoplanetary disk at the birth of the solar system, these organic may retain the memory of their previous irradiation processes. This master project will focus on developing a new setup to probe the effects of VUV irradiations on organic solids and their role as a source of complex molecules in the interstellar medium.

This work aims at being extended to help preparing future experiments on the available setups in our laboratories and on accelerators in which the applicant would be involved. The characterization of the irradiated analogues would extend the expertise to IR/Raman spectroscopies and comparison to astrophysics observatories data. They will set the preparation of eventual future observations with the next generation space telescope JWST, that will be launched in 2020 with expected exploitation duration of 5 to 10 years, providing a wealth of interstellar dust spectra to be interpreted via these experiments.
Laboratory experiments will be performed using low-pressure plasma sources to produce dust analogues. The experiments will make use of RF ultraviolet photon sources to irradiate them, cryogenic samples to place them at the low temperatures encountered in space (10K), in high vacuum chambers. Other characterizations may include tabletop spectrometers, quadrupole mass spectrometry, IR spectroscopy, visible-UVspectra.

The final goal includes :
- Analyses and comparisons to observational astronomical spectra
- Constraining the relative importance of production/destruction mechanisms of the solid organic matter in the interstellar medium
- Follow the evolution of solid matter in the radiative environment found in the interstellar medium (physico-chemical nature, ejection of radicals/molecules in the gas phase)
- Better define of the carriers associated with astronomical spectra observed by large actual or coming telescopes.