Characterization of the cutting edge of glass and diamond knives for ultramicrotomy by scanning force microscopy using cantilevers with a defined tip geometry. Part II.

The cutting edge of glass as well as diamond knives was studied at high resolution using a scanning force microscope (SFM). The local shape of the cutting edge was estimated from single line profiles of the SFM topographs taking into account the exact shape of the probing tip estimated by a high-resolution field emission scanning electron microscope (FESEM). The glass knives were prepared by 'balanced breaking'. The radius of the investigated cutting edges was found to be 3.2-4.4 nm and 4.3-6.0 nm for the 35 degrees and 45 degrees diamond knife, respectively, and 3.4-4.3 nm for the glass knives. Besides the opening angle and the cutting edge radius, the friction of a knife during sectioning represents a significant factor influencing the quality of sections. Thus, the roughness of both the diamond clearance angle side and the back side was characterized as well. Corresponding RMS values of the roughness were found to be smaller on the back side (approximately 0.14 nm) than on the clearance angle side (approximately 0.26 nm).