chapter  11
20 Pages

Chapter 11

Abstract ............................................................................... 524 11.1 Introduction ................................................................ 524 11.2 Experimental Procedure ............................................. 525 11.3 Sample Results and Analysis .................................... 527 11.4 Conclusions ................................................................. 539 11.5 Discussion of Future Work ........................................ 540 References............................................................................. 541

ABSTRACT

Ion-beam enhancement and detection of latent fingerprints using Auger and SIMS analysis have potentially significant forensic applications. The ion implantation process is used to ion-beam mix the materials of latent fingerprints into a substrate, such that the atoms that form the latent fingerprints become an integrated part of the substrate material. This now permanent record of the fingerprint can be imaged optically or with a scanning electron microscope. In addition, surface analysis techniques such as secondary ion mass spectrometry, particle induced x-ray emission or Auger electron spectroscopy can be used to identify the chemical composition of the fingerprint material. Once identified, the elements, molecular fragments and molecules unique to the fingerprint can be mapped using computer-assigned intensities to their relative abundance. The result is a computer-aided map of the latent fingerprint drawn with elements, molecules or molecular fragments. These can be of human origin or residue from the person leaving the fingerprint. A further benefit of the ion implantation process is that the fingerprint is permanently fixed in the substrate and can serve as a long-term record. This work involved ionbeam mixing fingerprints into selected classes of substrates and used Auger spectrometry and computer-aided Auger mapping to image fingerprints with low concentrations of the fingerprint materials. This combination of techniques produces images of fingerprints with surface analysis techniques that have not been previously applied. The application of these surface analysis techniques is made possible by the ion-beam mixing process. Applications are now possible utilizing techniques that are more sensitive to lower concentrations of fingerprint material than those currently being used by the forensic community. Using modern surface spectroscopy methods it is possible to detect and map fingerprints at very low concentrations.

11.1 INTRODUCTION