Coordination effect enhanced visualization of latent fingerprint with Eu (TTA)3phen-SiO2 microspheres

Latent fingerprint (LFP) powders are crucial in the detection of LFPs in forensic science. However, it is often plagued by poor image resolution and low contrast. Herein, enhanced LFP fluorescence (FL) visualizations are achieved by doping Eu(III) coordination compound Eu(TTA) 3 phen directly into SiO 2 microspheres instead of Eu(III) ions. Using the synthesized Eu(TTA) 3 phen-SiO 2 microspheres , the fine characteristic structure of LFP can be seen and recognized under 365 nm irradiation, up to Level 3. However, the Eu 3+ -SiO 2 microspheres were difficult to recognize the Level 2,3 fingerprint structure. The difference between the ridge and furrow gray values of Eu(TTA) 3 phen-SiO 2 microspheres is 2.1 times that of Eu 3+ -SiO 2 microspheres. The coordination effect increased the asymmetry around Eu(III) ions, resulting in the ultrasensitive 5 D 0 → 7 F 2 transition, thus increasing the FL intensity , and the uniform doping of the Eu(III) coordination compound into SiO 2 also reduced the surface FL quenching due to shielding from oxygen. Under this dual effect, the LFP performance of Eu(TTA) 3 phen-SiO 2 microspheres has been significantly improved. We believe that this novel and easy LFP visualization method is a promising routine in specific target detection including criminal investigation, customhouse check-in, and drug control.