This is the Final Summary Overview of a project whose goal was to determine whether Raman data obtained from the three-colored microscopic dots of inkjet printed documents constitute a chemical signature sufficiently discriminating to provide reliable investigative leads.
The three objectives involved in achieving this goal were to 1) develop an objective chemometric approach that can reliably differentiate between samples from different sources based on minor spectral differences; 2) assess whether different ink color dots from the same source can be treated as independent information; and 3) compare with the traditional method of thin layer chromatography (TLC) to inform questioned document examiners about the complementary connection between the two approaches. Raman spectroscopy differentiated spectral patterns based on the presence of Raman bands at a given wave-number value (x-axis), their width (bands compared to sharp peaks), and their relative intensities (height of a band relative to the height of another band). Spectral differences were noted in cases where the general Raman patterns of different samples were indistinguishable except for a low number of minor peaks often of minor intensity. This study is expected to contribute to the adoption of a chemometric approach that uses a large quantity of spectroscopic data (Raman patterns) in the early stage of an investigation. Listing of 5 anticipated project publications.