EELS, inverse and direct photoemission of pyrazine on Ag(111)

Pyrazine (C4N2H4) is probably adsorbed with the molecular plane parallel to the Ag(111) surface, because π-π* transitions measured by electron energy loss spectroscopy (EELS) are screened. The inverse and direct photoemission spectra are discussed within the framework of dipolar selection rules. A strong affinity level of pyrazine 2.6 eV above the Fermi level is tentatively assigned to b3u(π*). The tentative assignment of the photoemission spectra implies a relaxation of about 1.1 eV. © 1986.