In this paper we develop a hybrid QM/MM-MD direct dynamics method for the study of Ar and 0 scattering from room temperature ionic liquids (RTIL) at hyperthermal energies with the goal of providing an understanding of the reactivity of ionic liquids as potential hypergolic fuels The RTIL is chosen to be 1-ethyl-3-methylimidazolium nitrate ([emim][NO3]) as the bulk properties of this have been analyzed experimentally and theoretically and a force field has been developed Within our simulation time of 7 3 ps Ar collisions with the liquid surface cause, 2-3 proton transfers to occur from the imidazolium ring to the anion and a small fraction of these events leads to the desorption of neutral "emim or HNO3 species These change transfer processes also occur for O(P-3) collisions but in addition there is a rich amount of chemical change at the surface leading to four main collision types reaction with NO3 to form species like [NO2] ancl O-2 O addition to the imidazolium ring causing ring scission H abstractions from the hydroc ubon chains (ethyl or methyl) or imidazolium ring generating OH and 0 atom inelastic scattering Within the MSINDO model the major scattered products (all are neutral) from the 0 collisions, with their probabilities in parentheses are O (0 13) emim (0 12) HNO2 (0 05) HNO3 (0 04) and OH (0 04) Of these products only 011 is unique to O atom collisions, the HNO2 and HNO3 products also arise when the incident atom is Ar or 0