Construction and calibration of an instrument for 3D ion imaging

PHYS 374

Konrad Koszinowski1, Noah T. Goldberg, ntg@stanford.edu1, Andrew E. Pomerantz2, and Richard N. Zare, zare@stanford.edu1. (1) Department of Chemistry, Stanford University, Mudd Chemistry, 333 Campus Dr, Stanford, CA 94305-5080, (2) Schlumberger-Doll Research, 36 Old Quarry Rd, Ridgefield, CT 06877
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 ≤ λphotolysis ≤ 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. Preliminary results will be presented for bimolecular reactive scattering.

Poster Session
7:30 PM-10:00 PM, Wednesday, 13 September 2006 Moscone Center -- Hall D, Poster

8:00 PM-10:00 PM, Monday, 11 September 2006 Moscone Center -- Hall D, Sci-Mix

Division of Physical Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006