Molecular synthesis in hypervelocity impact plasmas on the primitive Earth and in interstellar clouds

Abstract

When impact speeds exceed a critical range of ∼15–20 km s−1, the resulting plasma plume energizes very rapidly from a few eV, to as high as 30–50 eV when speeds reach 50–100 km s−1, and can be completely atomized and ionized. During post‐impact adiabatic dispersion, the degree of ionization drops. The remaining ion population is mostly atomic, sampling the elemental composition of the colliding bodies, but some molecular ions are also formed. We present here results of experiments in which the physical and chemical conditions in the plume of a hypervelocity micrometeorite impact well above 20 km s−1 were modeled with Q‐switched laser ablation. The formed molecular ions were analyzed with a time‐of‐flight (TOF) mass reflectron capable of distinguishing plasma‐synthesized from surface‐desorbed species. Singly‐ and multiply‐charged small organic molecules were identified as having formed in laser plasmas induced from inorganic carbonaceous substances. The results show the possibility of abiogenic synthesis of organic molecules in hypervelocity impacts of meteors on the primitive Earth during heavy bombardment and of dust particles in interstellar clouds.