THIN AND ULTRA-THIN FILMS OF NICKEL PHTHALOCYANINE GROWN ON HIGHLY ORIENTED PYROLITIC GRAPHITE - AN XPS, UHV-AFM AND AIR TAPPING-MODE AFM STUDY

Thin and ultra-thin films of nickel phthalocyanine have been deposited in ultra-high vacuum on highly oriented pyrolitic graphite. The growt h mode and the interaction with the substrate have been studied in sit u by X-ray photoelectron spectroscopy, scanning tunneling microscopy a nd atomic force microscopy, and ex situ by means of tapping-mode atomi c force microscopy We present photoelectron spectroscopy measurements al various film thicknesses which show no detectable interaction of th e adsorbed organic layers with the substrate, but, varying the deposit ed film thickness by in-situ annealing the substrate, we show desorpti on effects semiquantitatively described. The XPS spectrum of the C Is multiplet structure of Ni-PC obtained using a monochromatized source i s also presented. The scanning probe images presented address morpholo gical issues like the growth mode at initial stages of deposition and at higher coverages. Moreover, upon annealing of the PC films, we show high-resolution measurements consistent with the low-size stable I cr ystalline phase of phthalocyanine molecules. The potential of tapping- mode atomic force microscopy in imaging soft adlayers deposited over s oft substrates is addressed throughout the paper. (C) 1997 Elsevier Sc ience B.V.