Site-specific ion desorption of fluorinated phthalocyanine studied with electron-ion coincidence spectroscopy

Abstract

Auger electron photo-ion coincidence (AEPICO) and Auger spectra of fluorinated copper phthalocyanine (F 16CuPc) were observed to study the mechanism of the site-specific ion desorption. From the photon energy dependence of Auger electron spectra at fluorine (F) K-edge region, it is found that the spectator-Auger shift at hν = 691.4 eV is about 2 eV. To estimate the contribution of spectator-Auger component to the Auger spectra, the difference Auger spectra were obtained by subtracting the Auger spectrum above F 1s ionization energy from observed Auger spectra. AEPICO yield spectra for F + at hν = 691.4 eV gives a large intensity at E kin = 650 eV. The electron kinetic energy position of this intense F + AEPICO peak agrees with that of the difference Auger spectra, indicating that the most probable mechanism for F + ion desorption induced by the transition from F 1s to σ(C F) * is the spectator-Auger-stimulated ion desorption.