Refining Fingermark Development using Diacetylene Copolymers on Difficult Surfaces^,

Abstract

In further work investigating the intriguing application of diacetylene copolymers in fingermark detection, methods were developed to control (inhibit or enhance) the diacetylene polymerization reaction in fingermarks treated with a mixture of the monomers 2,4-hexadiyne-1,6-bis-(phenylurethane) (HDDPU) and 2,4-hexadiyne-1,6-bis(p-chlorophenylurethane) (HDDCPU) in acetone solution. These methods included the use of a humidity chamber to reduce the amount of background development while promoting development on the fingermark, subjecting developed fingermarks to freezing temperatures and using a solvent to remove unreacted monomer in order to inhibit the polymerization reaction. Developed fingermarks were enhanced by conventional lighting (white light, filtered light) and fast Raman mapping, which was shown to be advantageous over FTIR imaging. This study also demonstrated the applicability of diacetylene copolymer solutions in the covert detection of fingermarks on difficult surfaces. Furthermore, fingermarks were successfully developed with good ridge detail on pig skin (used as a model for human skin, a notoriously difficult surface on which to develop fingermarks).

What can Raman spectroscopy do for criminalistics?

“…Raman mapping was also employed in a very recent study to detect fingerprints. Stojanovska et al prepared fingerprints on various surfaces, developed the prints with polymerization techniques, and then analyzed them with fast Raman mapping . They found Raman spectroscopy to be superior to Fourier transform‐infrared methods based on the high intensity of Raman peaks from the polymerizing agents, and the Raman shift of the peaks, which were very unique.…”

“…Adapted from Sikirzhytskaya, A. et al [52] and then analyzed them with fast Raman mapping. [55] They found Raman spectroscopy to be superior to Fourier transform-infrared methods based on the high intensity of Raman peaks from the polymerizing agents, and the Raman shift of the peaks, which were very unique.…”