Ultra low energy O2+ SIMS depth profiling of superficial poly(CuPc) and Co(II)T(o-NH2)PP monomolecular layers


R. J. H. Morris, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK.



Using an O2+ beam at 90 eV, close to the sputtering threshold, we have obtained depth profiles from superficial monolayers on gold. The samples were polymeric copper phthalocyanine (poly(CuPc)) (C32H12N8Cu)n and Co(II)T(o-NH2)PP (5,10,15,20-tetrakis-(2-aminophenyl) porphyrin-cobalt(II)) (C44H28CoN4) monomolecular layers, deposited on gold films on silicon. The layer thicknesses, determined using atomic force microscopy, were ~4.5 nm for the poly(CuPc) and ~1.8 nm for the Co(II)T(o-NH2)PP. The ion signals monitored included: poly(CuPc) layer: 63Cu+, 65Cu+, 30ON+ and 12 C+; Co(II)T(o-NH2)PP layer: 59Co+, 30ON+ and 12 C+. Comparisons between 90 eV and 235 eV profiles from the layers and bare substrates showed that the monomolecular layers are resolvable at 90 eV and distinct from any surface contamination spike. Copyright © 2012 John Wiley & Sons, Ltd.