High-contrast multi-surface imaging of latent fingerprints using color-tunable YOF:Tb³⁺,Eu³⁺ ultrafine nanophosphors...

Visualization of latent fingerprints (LFPs) using conventional powders has faced challenges on multicolor surfaces. However, these challenges are addressed by the advent of fluorescent powders in LFP detection, and they have redefined the effectiveness of the powder dusting method. In this study, color-tunable YOF:Tb³⁺,Eu³⁺ nanophosphors were examined for LFP recognition and were evaluated for their practicality on different types of surfaces. Under 254 nm UV irradiation, the LFPs developed using these nanophosphors showed clear and distinct ridge patterns with level 1, 2, and 3 details. The ultrafine particles of these nanophosphors adhered to the ridge patterns and replicated the minutiae of the LFPs. Meanwhile, the variation of the Tb³⁺/Eu³⁺ ratio demonstrated multicolor fluorescence emission from the nanophosphors, which provided better contrast between the ridge patterns on complex surfaces. Furthermore, the high luminescence quantum yield of the nanophosphors ensured high-resolution fluorescence images of the LFPs with a well-defined pattern that was recognizable even without any microscope or sophisticated instrumentation.