In the framework of the Nanocosmos ERC synergy project, a new analytical experimental setup called AROMA (Astrochemistry Research of Organics with Molecular Analyzer) was developed. The main purpose of this setup is to study and identify, with micro-scale resolution, the molecular content of cosmic dust analogues, including the stardust analogues that will be produced in the Nanocosmos Stardust machine in Madrid. AROMA combines laser desorption/ionization (LDI) techniques with a linear ion trap coupled to an orthogonal time of flight mass spectrometer (LQIT-oTOF). A first paper “Identification of PAH Isomeric Structure in Cosmic Dust Analogues: the AROMA setup” has just been published in The Astrophysical Journal. This is the first time that two-step LDI is coupled to a linear ion trap with MS/MS capabilities. In MS/MS experiments ions are first stored in a trap and then are fragmented under the action of photon or collision activation. The resulting fragments are then detected by mass spectrometry providing information on the molecular structure of the parent species.

The article presents the performances of AROMA with its ability to detect with very high sensitivity aromatic species in complex materials of astrophysical interest and characterize their structures. A two-step LDI technique was used, in which desorption and ionization are achieved using two different lasers which are separated in time and space. The tests performed with pure polycyclic aromatic hydrocarbon (PAH) samples have shown a limit of detection of 100 femto-grams, which corresponds to 2×10⁸ molecules in the case of coronene (C₂₄H₁₂). We detected a mixture of PAH small and medium-sized PAHs in the Murchison meteorite that contains a complex mixture of extraterrestrial organic compounds. In addition, collision induced dissociation experiments were performed on selected species detected in Murchison, which led to the first firm identification of pyrene (C₁₆H₁₀) and its methylated derivatives in this sample.

AROMA setup, being highly sensitive, selective, spatially resolved, and owing the MS/MS capabilities enables unique chemical characterization of aromatic species in cosmic dust analogues and extraterrestrial samples. Changing the ionization source will enlarge the scope of investigated chemical species. In the future, it will be used to analyze samples from the Stardust machine, other laboratory analogues and cosmic materials such as meteorites, and interplanetary dust particles. Currently, we are developing an imaging source that will allow us to analyze samples using LDI with micrometer spatial resolution.

This research was presented in the paper “Identification of PAH Isomeric Structure in Cosmic Dust Analogs: The AROMA Setup“, published in the Astrophysical Journal (APJ), 843:34 (8pp), 2017 July 1.  The authors are Hassan Sabbah (Université de Toulouse, UPS-OMP, Institut de Recherche en Astrophysique et Planétologie (IRAP); CNRS, IRAP; LCAR, Université de Toulouse, UPS-IRSAMC, CNRS, France), Anthony Bonnamy (Université de Toulouse, UPS-OMP, IRAP; CNRS, IRAP, France), Dimitris Papanastasiou (Fasmatech Science + Technology, Greece), Jose Cernicharo (Instituto de Ciencia de Materiales de Madrid (ICMM), CSIC, Spain), Jose-Angel Martín-Gago (ICMM-CSIC, Spain), and Christine Joblin (Université de Toulouse, UPS-OMP, IRAP; CNRS, IRAP, France).