Upconverting nanodots of nayf4yb3er3 synthesis characterization and uv visible luminescence study through ti sapphire 140 femtosecond laser pulses

In this work, dot-sized upconversion nanocrystals (UCN-dots) with diameter c.a. 3.4-0.15 nm have been synthesized. These UCN-dots exhibit visible emission (at 497, 527 and 545 nm) under the excitation with 980 nm CW-NIR laser. Further, these UCN-dots exhibit high energy upconversion emission (UV region, 206 to 231 nm) with Ti-Sapphire Femtosecond laser of 140-femtoseconds duration at 80 MHz repetition rate at different excitation, which has never been reported. This is interesting to report that the generation of high energy UV-Vis emission and their shifting from 206 to 231 nm for the UCN-dots by tuning the excitation wavelength ranging from 950 nm to 980 nm irradiated from Ti: sapphire Femtosecond laser observed. We have demonstrated the generation of high energy upconversions with change in energy band gaps as well as number of absorbed photons per photon emitted under the Femtosecond-laser excitation power. Additionally, we report the photo luminescence of UCN-dots in visible range with 450 nm excitation wavelength exhibiting blue and red emission (visible to visible). The generation of high energy up-conversion in UV-Vis region could be useful for designing optoelectronic and biomedical devices for therapeutic application.