Inelastic Scattering of Radicals at the Gas–Ionic Liquid Interface: Probing Surface Dynamics of BMIM–Cl, BMIM–BF4, and BMIM–Tf2N by Rovibronic Scattering of NO [2Π1/2(0.5)

Abstract

Quantum state resolved inelastic collision dynamics at the gas–room temperature ionic liquid (RTIL) interface have been explored by scattering of an NO projectile beam, with laser induced fluorescence (LIF) detection yielding detailed distributions in vibrational, rotational, and spin–orbit degrees of freedom. Collision energies are varied by seeding 1% NO in either first run Ne (70% Ne/30% He, 2.7(9) kcal/mol) or pure H2 (20(6) kcal/mol), with the incident NO beam skimmed and colliding at 45° with respect to the surface normal. At E = 2.7(9) kcal/mol, NO scattering in the 2Π1/2 state is well characterized by a rotational Boltzmann distribution equilibrated with the surface temperature, characteristic of trapping desorption (TD) collision dynamics. At higher collision energy (E = 20(6) kcal/mol), however, significant rotational excitation is observed, suggesting impulsive scattering (IS) dynamics where desorption occurs before the species has achieved full thermal equilibration with the surface. NO scatte...