Latent fingermarks detection for La2O3:Er3+/Yb3+ phosphor material in upconversion emission mode: A comparative study

The authors in this manuscript present the results on synthesis of Er3+/Yb3+ codoped La2O3 upconverting phosphor and its demonstration on the development of latent fingermarks on the surfaces of semi-porous and non-porous objects. The samples were synthesized via combustion using urea as a reducing agent and chemical precipitation methods. The annealed samples showed enough intense green emission in the 520–550 nm range on 980 nm excitation. Excellent emission property of the samples in the green region showed an advantage to use it in latent fingermarks detection. A dry powder dusting technique is used to develop latent fingermarks and the results are compared. The studies reflected the superiority of upconversion phosphor materials for the detection of latent fingermarks over the traditional downconversion luminescence methods.