Interstellar Molecules Laboratory Spectroscopy and Synthesis (IMOLABS)

Molecular spectral lines are excellent diagnostics of the composition and physical conditions of the diffuse matter where they are formed, from comets and planetary atmospheres to star forming regions, interstellar clouds, planetary nebulae to galaxies near and far. The full analysis of astronomical observations requires a detailed knowledge of the molecular spectral properties, that can only be achieved by detailed laboratory work. The goal of this project is to jointly develop new techniques for molecular spectroscopy in the laboratory, combined with advances in the synthesis of complex molecules, expected to contribute to the wealth of unidentified feature in astronomical spectra.

We have selected a list of key species, that are expected to be present in the interstellar medium, or in dense planetary atmospheres like that of Titan, or in evolved star atmospheres. The common thread of these environments is the combined role of energetic processes (due e.g. to far UV (FUV) photons or cosmic rays) and solid phase reactions in the formation pathways of molecules. The selected species should provide interesting information on the formation pathways of interstellar molecules, but that lack accurate rotational spectroscopy so far.

• The first part of the project is dedicated to the development of synthesis methods for interstellar molecules. As most of the targets can not be found easily, they need to be produced in situ. We propose to develop advanced organic synthesis methods of the molecules themselves or of molecular precursors that form the molecule in the spectrometer cell. An alternative technique could be the use of a discharge in gas mixture. We propose to evaluate the feasibility of this technique during the project.
• The second part of the project is the laboratory spectroscopy work, for the selected species, radicals and ions., including the acquisition of the spectra and their analysis.
• The third part of the project is the development of the molecular spectroscopy techniques, with the increase of the frequency coverage to 2THz, and the implementation of a heterodyne detection system on the spectrometer, to improve the sensitivity and the instantaneous bandpass of the spectral detection.
• The last part of the project is the astronomical search for the selected species, and the modeling of their abundances. It will be based on state of the art chemical and radiative transfer models, and will use available spectral line data (private spectral survey and publicly available data from e.g. the Herschel archive). New observation programs will also be prepared for deep searches of specific molecules with ALMA or IRAM/NOEMA.

This project is jointly prepared by M. Gerin (LERMA), L. Margulès (PhLAM) and J.C. Guillemin (ENSCR).