Inner-shell photoelectron angular distributions from fixed-in-space OCS molecules

The photoelectron angular distributions (PADs) for the OCS O 1s, C 1s and S 2p_1/2, 2p_3/2 ionization have been measured in the shape resonance region. The experimental results have been compared with multiple scattering Xα calculations. It is found that the position of an ionized atom plays a significant role. For a central position (C Is ionization) the PAD is relatively symmetric. In the case of S 2p and O 1s ionization, electrons are emitted highly preferentially in a solid cone directed from the molecular centre to the respective S or O atom. For the OCS O Is ionization the S-C fragment plays a very effective role as a 'scatterer' and in the shape resonance region nearly all intensity in PAD is concentrated in the lobe between θ = 50° and 80°, but not along the molecular axis.