Presence of Particles on Melt-Cut Mica Sheets

We show the presence of numerous particles on mica surfaces melt-cut for use in the surface force apparatus (SFA). The particles, as observed by atomic force microscopy, are typically 20−25 nm in diameter and 2−3 nm high, and cover up to 0.05% of the surface area. They consist of solidified droplets of molten mica, scattered across the surfaces during the cutting of cleaved mica with a white-hot platinum wire. The particles adhere strongly to the mica surfaces in inert atmospheres but become mobile and disappear upon scanning under water and polar liquids. They seem to remain attached to the surfaces in nonpolar liquids. The particles appear to affect to a noticeable extent only experiments involving capillary condensation of water between mica surfaces.