Near-threshold Cooper minimum in the photoionisation of the 2p subshell of sodium atom and its impact on the angular distribution parameter

Abstract

The present work reports the photoionisation studies of 2p subshell of Na atom, just above the threshold region. The calculations are performed in the framework of multiconfiguration Dirac–Hartree–Fock method (MCDHF). It unravels the effect of 3d orbital on the final state leading to the appearance of Cooper minimum (CM) in the region close to the threshold. Further, the impact of this CM on the angular distribution parameter is studied. It is found that CM not only modifies the cross section profile but also makes dramatic changes in the angular distribution.