Photodissociative pathways of C2H2 at 121.6 nm revealed by a Doppler-Selected time-of-flight (a 3-D mapping) technique

The photodissociation dynamics of C2H2 near the H-atom Lyman-a transition was investigated by a newly developed, Doppler-selected time-of-flight technique. The aim of this study is to elucidate the detailed dynamics via the directly measured fragment 3-D distribution. An alternative, preliminary analysis of a fraction of the data is presented here which already reveals a rich dynamics involved in the photodissociation. A strong propensity against the formation of the ground electronic CxH((X) over tilde 2 Sigma) state, a prominent C-H stretching excitation in the production of the C2H((A) over tilde) state, and two distinct dissociation pathways being likely involved in the title process have been found.