Red and green colors emitting spherical-shaped calcium molybdate nanophosphors for enhanced latent fingerprint...

We report the synthesis of spherical-shaped rare-earth (Eu³⁺ and Tb³⁺) ions doped CaMoO₄ nanoparticles in double solvents (IPA and H₂O) with the help of autoclave. The X-ray diffraction patterns well match with the standard values and confirm the crystallization in a tetragonal phase with an I4₁/a (88) space group. The luminescence spectra exhibit the strong red and green emissions from Eu³⁺ and Tb³⁺ ions doped samples, respectively. The X-ray photoelectron spectroscopy results show the oxidation states of all the elements present in the sample. The temperature-dependent luminescence spectra reveal the stability of Eu³⁺ and Tb³⁺ ions doped samples. The red- and green-emitting Eu³⁺ and Tb³⁺ ions doped CaMoO₄ samples were used for detection and enhancement of latent fingerprints which are the common evidences found at crime scenes. The enhanced latent fingerprints obtained on different surfaces have high contrast with low background interference. The minute details of the fingerprint which are useful for individualization are clearly observed with the help of these nanopowders.