One of the ultimate goals in the field of reaction dynamics is to be able to measure the angular distribution of

products in a quantum-state-specific manner. As a step in this direction, we report the first application of ion imaging to a bimolecular reaction. We study the H + HI --> H2 + I reaction in a neat supersonic molecular

beam of HI. The supersonic expansion provides a reaction precursor possessing a very narrow thermal velocity distribution. By avoiding a thermally equilibrated HI source (e.g., an effusive beam, or bulb), the center-of-mass collision energy spread has been substantially reduced. Fast H atoms are formed by laser photolysis of HI, and the H2 (v= I,J= 11,13) products are ionized by (2 + 1) resonance-enhanced multiphoton ionization (REMPI)

before being imaged onto a position-sensitive detector. In this way we have measured the laboratory-frame velocity distribution of the state-selected reaction products. Early dynamical studies of the H + HI abstraction reaction attempted to measure the angular distribution of the molecular product but failed because of background problems.More recently, internal state distributions of the molecular product have been determined, but without angular information.