Topography investigation of water layer and self-assembled monolayer with OTS-modified AFM tips

The imaging process with atomic force microscopy (AFM) in air is influenced by many factors, such as tip size and geometry, scan speed, ambient humidi ty, etc. In an ambient environment the imaging can be affected greatly by t he humidity of the atmosphere because of the formation of the meniscus alon g the tip-sample interface. The capillary force between the tip and the sam ple is generally large enough to make it difficult to obtain a high-resolut ion image, therefore it is necessary to eliminate this capillary in order t o obtain improved images. To this end, we modified tips with CH3-terminated organosilane to make them hydrophobic. With such tips we obtained (in AFM/ LFM mode) improved images of soft materials such as the water layer and the self-assembled monolayer (SAM). For octadecantrichlorosilane (OTS) SAM che misorbed on mica, high-resolution lattice-resolved images also were collect ed. The results demonstrated that these hydrophobic tips were suitable for obtaining improved images. Copyright (C) 2001 John Wiley & Sons, Ltd.