AVS 46th International Symposium
    Applied Surface Science Division Wednesday Sessions
       Session AS-WeM

Paper AS-WeM9
Naphthalocyanine Molecules onto Si(111)7x7 and Si(100)2x1: Modes of Adsorption and Effects of Oxygen Doping Investigated with XPS

Wednesday, October 27, 1999, 11:00 am, Room 6A

Session: Gaede-Langmuir Award Address and Quantitative Surface Analysis
Presenter: L. Lozzi, University of L'Aquila and INFM, Italy
Authors: L. Ottaviano, INFM, Italy
L. Lozzi, University of L'Aquila and INFM, Italy
A. Montefusco, University of L'Aquila and INFM, Italy
S. Santucci, University of L'Aquila and INFM, Italy
Correspondent: Click to Email
We have deposited in ultra high vacuum various thickness of metal free naphthalocyanine (H@sub 2@NPc) onto Si(111)7x7 and Si(100)2x1 and studied in situ the interfaces by means of standard monochromatized X-ray Photoelectron Spectroscopy.@footnote 1@,@footnote 2@ By comparing the core level N1s and C1s spectra obtained for the pure molecule with those typical of the interface at submonolayer and intermediate level of deposition we derived information on the ways of adsorption of the isolated molecules onto the substrates used. In particular NPc adsorbs planarly to the Si(111)7x7 substrate showing strong chemisorption effects involving all the atoms of the molecule. On the other hand, the chemisorption involves only two C atoms when using the Si(100)2x1 substrate. In this case the NPc molecules are likely to be adsorbed in a out of planar mode. In a dedicated series of experiments, the interfaces have been doped with oxygen. An integer ratio of the estimated oxygen atoms per Naphthalocyanine (NPc) molecule in the quantitative XPS elemental analysis of the spectra gives evidence for a preferential adsorption of oxygen in molecular form onto NPc. A careful analysis of the spectra indicates that oxygen mainly interacts with the inner porphyrin structure of the molecule. @FootnoteText@ @footnote 1@ L. Ottaviano, L. Lozzi, and S. Santucci, Surf. Sci. (in press). @footnote 2@ L. Ottaviano, L. Lozzi, A. Montefusco, and S. Santucci, Surf. Sci. (submitted).