Versatile core–shell SiO2@ SrTiO3: Eu3+, Li+ nanopowders as fluorescent label for the visualization of latent fingerprints and anti-counterfeiting applications.

Abstract

To overcome shortcomings encountered in enhancing the quality of latent finger prints (LFPs) by traditional powder dusting method, SiO2@SrTiO3:Eu3+ (1 mol %), Li (1 wt %) core–shell nanopowders (NPs) were prepared by using combustion process. LFPs were visualized by staining prepared samples on both porous and non-porous surfaces under the illumination of UV light of wavelength 254 nm. These LFPs reveals the detailed characteristic features such as lake, hook, island, bifurcation with high sensitivity, better selectivity and without background hindrance. SiO2@SrTiO3:EuLi NPs exhibited characteristic pure red emission peaks in the range of 530-760 nm which can be assigned to 5D0 7FJ (J = 0, 1, 2 and 3) transitions. By altering the number of coating cycles dim white light fluorescent to warm white emitting phosphors could be obtained with the single crystal phase. The spectral intensity parameters and Eu-O ligand behaviors were estimated by means of Judd-Ofelt (J-O) theory. The prepared core-shell SiO2@SrTiO3:Eu3+, Li NPs are explored as a fluorescent labeling agent for the visualization of latent fingerprints and anticounterfeiting applications.