title: Construction and calibration of an instrument for three-dimensional ion imaging.
abstract: We describe a new instrument based on a delay-line detector for imaging the complete three-dimensional velocity distribution of photoionized products from photoinitiated reactions. Doppler-free [2+1] resonantly enhanced multiphoton ionization (REMPI) of H and D atoms formed upon photolysis of HBr and DBr in the range 203 nm < or = lambda photolysis < or = 243 nm yields radial speeds measured to be accurate within 1% of those calculated. The relative speed resolution is about 5% and limited by photoionization recoil broadening. A relative speed resolution of 3.4% is obtained for [3+1] REMPI, which minimizes the ionization recoil. We also determine the branching ratio between ground-state and spin-orbit-excited product channels and their associated anisotropies. We find that DBr photolysis dynamics differs slightly from its HBr counterpart.
authors.affiliation: Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA.
authors.forename: Konrad
authors.initials: K
authors.lastname: Koszinowski
authors.forename: Noah T
authors.initials: NT
authors.lastname: Goldberg
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Pomerantz
authors.forename: Richard N
authors.initials: RN
authors.lastname: Zare