Oriented molecule beams: Focusing and orientation of t-butyl bromide with analysis by polarized laser photofragmentation.

Tert-butyl bromide is photodissociated at 277.3 nm (in the tail of the first absorption continuum). Both fragments, i.e., the t-butyl radical and the Br(2P1/2) atom, are detected by laser MPI-TOF mass spectrometry. Seeded, supersonic beams of this pseudosymmetric top molecule are readily focusable and orientable (via its first-order Stark effect) using the electrostatic hexapole lens. The linearly polarized laser-induced photofragmentation technique reveals unusually high degrees of orientation, significantly greater than that for t-C4H9I, due to the less serious hyperfine disorientation effect for the Br- (vs I-) containing molecule. Thus t-C4H9Br is an excellent candidate reagent for reactive asymmetry scattering studies of the steric effect via the oriented molecule beam method. [ABSTRACT FROM AUTHOR]