H Atom migration in C2H3+

Abstract:
This talk will begin with a pictorial explanation of the H atom migration motion in protonated acetylene. It will then review the sub-millimeter wave measurements (166 to 470 GHz) of the Lille group in the vibrational ground state, and describe possible additional ground-state measurements at higher frequencies. It will then give a brief qualitative description of the high-barrier generalized Internal-Axis-Method Hamiltonian used by Cordonnier and Coudert to fit the ground state H-migration-tunneling splittings. These splittings are unfortunately less than 500 kHz and only partially resolved. Finally the talk will discuss infrared measurements from Oka’s group in the 3um (CH stretching) region, where the tunneling splittings are of the order of 0.3 cm-1, and therefore easily resolvable, but where they are contaminated by numerous perturbations from dark states in the surrounding vibrational bath, and therefore difficult to fit theoretically.