Imaging of sub-surface nano particles by tapping-mode atomic force microscopy

Time-of-Right secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectr on spectroscopy (XPS), and tapping mode atomic force microscopy (TM-AFM) we re used to study the surface of a poly(N-vinyl-2-pyrrolidone) thin film con taining nano silica particles. ToF-SIMS results illustrate that the topmost layer of the thin film consists of PVP and a small amount of poly(dimethyl siloxane) (PDMS). Nano silica particles are localized underneath this laye r. XPS results suggest that the concentration of the silica particles incre ases as the sampling depth increases from 5.3 to 7.2 nm. TM-AFM phase imagi ng is shown to be capable of detecting the presence of these sub-surface na no silica particles. (C) 2000 Elsevier Science Ltd. All rights reserved.