Slice imaging is used to measure the alignment of Br(P-2(3/2)) and Cl(P-2(3/2)) photofragments from the photodissociation of HBr and HCl, respectively, at 193 nm. In both cases the A(1)Pi(1) state is predominantly optically excited, which correlates to m(J) = +/-3/2 for the halogen atom photofragments. However, both the Br and Cl photofragments are measured to populate mostly m(J) = +/-1/2, showing that for both HBr and HCl nonadiabatic transitions transfer more population to the a(3)Pi(1) state (which correlates to m(J) = +/-1/2) during dissociation than remains in the A(1)Pi(1) state. The interference between these two pathways is also measured. (C) 2002 Published by Elsevier Science B.V.