Modeling formation of molecules in the interstellar medium by radical reactions with polycyclic aromatic hydrocarbons

摘要

Adsorptions of CH°_2, CH°_3, NH°_2, and OH° radicals and molecule formation on a partially hydrogenated surface of a polycyclic aromatic hydrocarbon (PAH) (C _(24)H_(27)~+) were modeled. It was found that radical adsorptions are feasible with important modifications of surface bond strengths and bond distances. Adsorbed hydrogen may diffuse due to adsorbate-surface interactions. Formations of CH_4, NH_3, H_2O, CH_3NH_2, and CH_3OH were studied by Eley-Rideal (ER) and Langmuir-Hishelwood (LH) mechanisms. Potential energetic surfaces were performed for both mechanisms and the ER presents lower reaction energy barriers than the LH one, in all cases. Parametric quantum program (CATIVIC) was employed and comparisons with DFT results were performed.