Age dating of fingerprints can have a significant impact in forensic science, as it has the potential to facilitate the judicial process by assessing the relevance of a fingerprint found in a crime scene. However, no reliable method currently exists that can reliably predict the age of a latent fingerprint. In this manuscript, time-of-flight secondary ion imaging mass spectrometry (ToF-SIMS) was used to measure the diffusivity of squalene and fatty acid molecules from a fingerprint on a silicon wafer. It was found that their diffusion from relatively fresh fingerprints (t ≤ 96 hrs) could be modeled using an error function, with diffusivities (mm2/hr) that followed a power function when plotted against molecular weight. The nist-equation x=0.02〖 t 〗^0.5 was obtained for palmitic acid that could be used to find its position in mm (where the concentration is 50% of its initial value, or c0/2) as a function of time in t hrs.
tof-sims, chemical imaging, fingerprints, sebum, forensics, diffusion