  Both single-laser and two-laser experiments were conducted to look into the
ion-imaging of Br*(2P1/2) and Br(2P3/2) photo-fragmented from
1-bromo-2-methylbutane in the range 232-240 nm via a detection scheme of (2+1)
resonance-enhanced multiphoton ionization. The angular analysis of these
photofragment distributions yields the anisotropy parameter beta = 1.88 +/-
0.06 for the Br* excited state which arises from a parallel transition, while
beta = 0.63 +/- 0.09 for the Br ground state indicates the contribution from
both a perpendicular transition and a non-adiabatic transition. When a hexapole
coupled with an orienting field was implemented, the parent molecules are
spatially oriented to yield an orientation efficiency |<cos theta>| of 0.15.
Besides the chi angle between the recoil velocity v and the transition dipole
moment mu, orienting molecules allows for the evaluation of the angle alpha
between v and the permanent molecular dipole moment d. The angular analysis of
Br* photofragment distribution yields chi to be 11.5 degrees and alpha in the
range from 160 degrees to 180 degrees with weak dependency. In the two-laser
experiments, the angular anisotropy of Br photofragment distribution was found
to be smaller (0.38 +/- 0.10) when the photolysis wavelength was red-shifted to
240 nm, suggesting the increasing contributions from perpendicular transitions.
