Internal inelastic scattering satellite probed by molecular-frame photoelectron angular distributions from CO2

The molecular-frame photoelectron angular distribution (MFPAD) of the satellite accompanying the C 1s photoline of the CO(2) molecule has been measured at the C 1s(2 sigma(g))-> 4 sigma(u)* shape resonance, using electron-ion multicoincidence momentum spectroscopy. The observed MFPAD indicates that the conjugate satellite is excited by internal inelastic scattering. In this scenario, a photoelectron is ejected from the C 1s(2 sigma(g)) orbital along the molecular axis and collides with an O lone-pair electron in the highest occupied molecular orbital 1 pi(g). Then one of the colliding electrons is trapped to the lowest unoccupied molecular orbital 2 pi(u)*, while the other is emitted as a satellite photoelectron of sigma(g) symmetry, losing the information of the original photoelectron emission direction and parity.