Circular dichroism in photoelectron angular distributions from adsorbed atoms

The theory of circular dichroism in the photoelectron angular distributions (CDAD) of oriented linear molecules is applied to the photoionization of adsorbed atoms. CDAD is shown to offer much greater detail about the adatom than is available from standard angle-resolved photoionization studies. For oriented atomic orbitals, CDAD is shown to arise solely from interference between the l→l+1 and l→l-1 photoionization channels. In addition, for both adsorbed atoms and oriented molecules, CDAD is shown to arise entirely from the non-plane-wave nature of the final state. A simple calculation of CDAD from an oxygen-atom p orbital is given.