Eu2+,Dy3+ codoped SrAl2O4 nanocrystalline phosphor for latent fingerprint detection in forensic applications

In this work, europium and dysprosium doped strontium aluminate (SrAl2O4:Eu2+, Dy3+) nanophosphor is synthesized and its novel application for the detection of latent fingerprints on various contact surfaces is reported. The SrAl2O4:Eu2+, Dy3+ is synthesized using a combustion method and shows long-lasting afterglow luminescence. The powder particles are characterized using field emission scanning electron microscopy (FE-SEM), SEM-energy dispersive x-ray analysis, x-ray diffraction and photoluminescence spectrophotometry. The FE-SEM image analysis reveals that the nanoparticles are mostly 8-15 nm in size with an irregular spherical shape. This nano-structured powder was applied to fresh and aged fingerprints deposited on porous, semi-porous and non-porous contact surfaces, such as ordinary colored paper, glossy paper, glass, aluminum foil, a yellow foil chocolate wrapper, a soft drink can, a PET bottle, a compact disc and a computer mouse. The results are reproducible and show great sensitivity and high contrast in the developed fingermark regions on these surfaces. These nanophosphor particles also show a strong and long-lasting afterglow property, making them a suitable candidate for use as a fingerprint developing agent on luminescent and highly patterned surfaces. These kinds of powders have shown that they can remove the interference from background luminescence, which is not possible using ordinary luminescent fingerprinting powders.