Examination of line crossings by atomic force microscopy

Until now, the most widely used methods for the forensic examination of lin e crossings in documents were optical and electron microscopy. The combinat ion of both techniques allows one in most cases to establish the sequence o f lines. The recent development of scanning probe microscopy [1] gives an o pportunity to complement or even replace the classical instruments used in this field. Scanning probe microscopes have been designed to study surfaces at high magnification. The aim of this study was to verify if their most p opular member, the atomic force microscope (AFM) [2], can be applied to lin e crossing problems. The results show for the first time that AFM images pr esent the same qualitative information obtained by scanning electron micros cope (SEM) images and, consequently, allow the determination of the line cr ossing sequence under ambient conditions without vacuum and conductive coat ing of specimens. (C) 2001 Elsevier Science Ireland Ltd. All rights reserve d.