[Truncated abstract.] An apparatus has been built, tested and characterised with greatly increased precision and accuracy to enable spin-polarised electron impact explorations of angular momentum effects in atoms. A combination of experimental, computational and interpretative studies has revealed new phenomena. In zinc the polarisation of the radiated photons from excited and ionised-with-excited atoms was measured in terms of integrated Stokes parameters (P1, P2 and P3) and related to electron exchange and spin-orbit interaction using normalised state multipoles.