Versatile fluorescent CaGdAlO4:Eu3+ red phosphor for latent fingerprints detection

Abstract

Latent fingerprint detection is one of the promising technique in forensic science. Here, an oxide based red-emitting phosphors, CaGdAlO4:Eu3+ (CGA:Eu3+), have been successfully synthesized by a solvothermal reaction method. The structural phase was characterized with the XRD Rietveld refinement and TEM analyses. The luminescence properties and dynamics of Eu3+ in CGA were studied in detail by room temperature emission, excitation and decay curve measurements. Intense red emission peaking at 620 nm due to 5D0→7F2 transitions of Eu3+ under the excitation at 283 nm was obtained and the optimal Eu3+ ion concentration was found to be about 7 mol%. The CIE chromaticity coordinate evaluated from the PL spectra and exhibited (0.6410, 0.3581) coordinates within the pure red region of the CIE 1931 diagram with a close proximity to the commercial red phosphor (Y2O2S:Eu3+). Furthermore, with the use of the CGA:7Eu3+ phosphors, the developed latent fingerprint fluorescent images were well visualized and identified their level 1, 2 and 3 details with high contrast, selectivity and sensitivity. These results indicate that CGA:7Eu3+ has great potential for practical applications in the latent fingerprint detection.