AROMA Setup First Results

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. It 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.