Synthesis of Gd2O3:Ho3+/Yb3+ upconversion nanoparticles for latent fingermark detection on difficult surfaces

Effect of pH of Precursor on Up/Downconversion and Cathodoluminescence of Gd2O3:Ho3+/Yb3+ Phosphor and Magneto‐Optic Studies

“…The up/down conversion emission mechanisms have been explained in the energy level diagram Figure . In our previous report, the sensitization assisted energy transfer followed by ground state absorption (GSA)/ excited state absorption (ESA) upconversion mechanism for 539, 550 and 667 nm emission band with ( 5 F 4 , 5 S 2 , 5 F 5 ) → 5 I 8 transitions has already been discussed ,. For downconversion emission, the excitation transitions for 550 nm ( 5 S 2 → 5 I 8 ) emission are observed due to the 3 H 5 ← 5 I 8 , 5 G 4 ← 5 I 8 , 5 G 5 ← 5 I 8 , 3 K 8 ← 5 I 8 , 5 F 3 ← 5 I 8 transitions.…”

“…The up/downconversion emission from rare earth ion finds several applications discussed in the literature . In up/downconversion process, the emitted color is determined by the selection of dopants ion concentration and their combinations . Availability of lower phonon energy phosphors has greatly expanded the utility of Ho 3+ as a dominant activator dopant due to its favorable energy level scheme.…”

“…The Ho 3+ /Yb 3+ ion combination is an important pair that gives high upconversion emission in the green region on 980 nm diode laser excitation. Gd 2 O 3 has been considered as low phonon frequency host having maximum phonon vibration ∼530 cm −1 . Gd 2 O 3 also has high thermal stability and less hygroscopic compared to other efficient hosts such as La 2 O 3 due to Gd 3+ has its first excited state at 32,000 cm −1 and is optically inactive below this energy.…”

Nanoparticles used for fingermark detection—A comprehensive review

“…Kumar et al demonstrated the use of Gd 2 O 3 :Ho,Yb nanopowder and colloidal solution spray (Kumar, Tiwari, Singh, & Kumar, 2016). On the various substrates tested, the commercial green luminescence powder either had low contrast and less ridge detail or no ridge detail, whereas the NP powder and colloidal solution gave good contrast and clear ridge detail.…”

Commercial Upconversion Phosphors with High Light Harvesting: A Superior Candidate for High‐Performance Dye‐Sensitized Solar Cells

“…Upconvertion phosphors (UCPs) have received more and more attention due to their low phonon energy of lattices, and have been studied in the field of solar cells, solid‐state lasers, biomedical imaging, etc . Among all the investigated UCPs so far, hexagonal NaYF 4 (β‐NaYF 4 ) crystals doped with lanthanide combinations of Yb 3+ /Er 3+ were the most efficient upconversion materials .…”