PUB - Publikationen an der Universität Bielefeld

The photoionization of NO molecules is studied using angle- and spin-reserved photoelectron spectroscopy with circularly polarized synchrotron radiation. The spin-orbit splitting is resolved by preparing only the X (2)Pi(1/2) component of the ground state in a helium-seeded supersonic expansion. A pronounced spin polarization in the angular distribution is found for the cold beam when the strong autoionization resonance at 13.82 eV photon energy is excited. The polarization parameters A, xi and alpha are determined for the nu = 2 and 3 vibrational levels of the NO+ X (1)Sigma(+) final ionic state. The results lead to the conclusion that resonances with (2)Sigma(+) and (2)Delta symmetry contribute with similar intensity. The dominant contributions to the dipole transition matrix elements of the emitted electron waves can be derived approximately.