No forensic method exists that can reliably estimate the age of fingermarks found at a crime scene. Information on time passed since fingermark deposition is desired as it can be used to distinguish between crime related and unrelated fingermarks and to support or refute statements made by the fingermark donors. We introduce a non-contact method that can estimate the age of fingermarks. Fingermarks were approached as protein-lipid mixtures and an age-estimation model was build based on the expected protein and lipid oxidation reactions. Two measures of oxidation are required from the fingermark to estimate its age: 1) the relative amount of fluorescent oxidation products 2) the rate at which these products are formed. Fluorescence spectroscopy was used to obtain these measures. We tested the method on 44 fingermarks and were able to estimate the age of 55% of the male fingermarks, up to three weeks old with an uncertainty of 1.9 days.

Room-temperature deposited submonolayers of silicon on Si͑001͒ are investigated using STM. The observed structures and the mechanisms leading to their formation are discussed. Isolated ad-dimers in different geometries are described and a kinetic model for their formation is deduced. It is shown how further growth occurs via the formation of 3-atom clusters, which act as nucleation centers for the formation of two types of linear structures. One of the line types is formed in the ͓110͔ direction, and has been observed before. The other is in the ͓310͔ direction. At a coverage of nearly 0.2 ML a kind of random network consisting of segments of the two types of atomic lines is formed. Above 0.2 ML coverage these lines are converted into epitaxial dimer rows. A pathway for this conversion is proposed on the basis of experimental observations.

No abstract