The breaking of the backward-forward symmetry in the angular distribution of m_j-selected photofragments

We present calculations on the angular distributions of m_j-selected photofragments (with m_j being the projection of the fragments' internal angular momentum on a space-fixed z-axis). We show that the proper analysis of such experiments [based on G. G. Balint-Kurti and M. Shapiro, Chem. Phys. 61, 137 (1981)], involves coherent λ≠λ′ terms (with λ - the "helicity" - being the projection of the fragment angular momentum on the recoil direction). The involvement of these coherent terms leads, amongst other things, to the creation of "orientation," i.e., the backward-forward asymmetry, in the fragments' angular distributions. Thus we demonstrate that the detection of polarization in one (internal) variable - the internal rotation, creates a correlated orientation in another (external) variable - the recoil angular distribution.