Triply differential photoelectron studies of the four outermost valence orbitals of cyanogen

Photoelectron measurements, differential in incident wavelength, photoelectron energy and photoelectron ejection angle, have been performed on cyanogen, C₂N₂, from threshold to a photon energy of 24 eV, using synchrotron radiation. The results are presented in the form of photoionization branching ratios and photoelectron angular distributions, including vibrationally resolved results for the outermost orbital, 1π_g. Some evidence for resonant processes is observed and discussed within the framework of recent work on related molecules. However, reliable assignments require further theoretical guidance with regard to the location and identities of possible shape resonances and autoionizing intravalence transitions in the C₂N₂ spectrum.