Study of excited states of fluorinated copper phthalocyanine by inner shell excitation

Near edge X-ray absorption fine structure (NEXAFS) spectra of hexadecafluoro copper phthalocyanine (FCuPc) films (thickness of 50 Angstrom) on MoS2 substrates were observed near the carbon (C) and fluorine (F) K-edges. From the analysis of the dependence of C and F K-edge NEXAFS spectra on the photon incidence angle (alpha), the average molecular tilt angle was determined to be 30degrees. The lowest and second lowest peaks in the F K-edge NEXAFS were assigned to the transition to sigma*. In the ion time-of-flight mass spectra of FCuPc excited by photons near the F K-edge, F+, CF+, and CF3+ ions were mainly observed. These results indicate that C-C bonds as well as C-F bonds are broken by the photon irradiation. From the analysis of the partial ion yield spectra of F+ and CF+ near the F K-edge, the lowest and second lowest peaks in the F K-edge NEXAFS spectra could be assigned to transitions to sigma(C-F)* and sigma(C-C)*, respectively. (C) 2004 Elsevier B.V. All rights reserved.