Recoil Frame Research Articles

Angular momentum coupling in triatomic pre-dissociations

A quantum theory on angular momentum coupling in pre-dissociation processes of triatomic molecules is presented. The initially prepared state of an asymmetric top is first resolved into state vectors in the recoil frame by an addition theorem of spherical harmonics. Under the influence of an anisotropic, repulsive potential, the evolution of the pre-dissociative density matrix determines the subsequent angular momentum coupling between photofragments, including their interfragmental orbital angular momentum. The present framework provides a foundation to tackle the problem of pair-correlated angular distributions of photofragments from pre-dissociations of polyatomic molecules.

Coupled-channels calculation for the system 23Na+208Pb: a test of tidal symmetry

The results of a coupled-channels calculation for the elastic and inelastic scattering of 170 MeV 23Na by 208Pb are compared with the adiabatic model and the isocentrifugal model. It is shown that, in the absence of Coulomb excitation, the tidal spin is conserved to a very good approximation. The effect of Coulomb excitation is to cause deviations from tidal symmetry. It is shown that the extent to which tidal symmetry is satisfied becomes very transparent if the amplitudes and analysing powers are calculated in a recoil frame where the recoil direction is chosen as the z axis.