International Journal of Catalysis and Chemical Engineering
Multiphoton Absorption, Generation Of Higher Order Harmonics And Strong Blue - Emission From The Ultrasmall Upconverting Nanoparticles
Abstract
Monami Das Modak, Pradip Paik, Anil K Chaudhury and Nabanita Pal
Erbium, Ytterbium doped sodium yttrium fluoride nanocrystals (NaYF4:Yb3+ /Er3+) are promising candidates to be considered as the highly efficient upconverting nanomaterials. Herein, the generation of efficient higher order harmonics by five, four photon absorption processes (Multiphoton absorption- MPA) are revealed under the excitation with femtosecond-laser (fs-laser) with 140 fs-laser pulses in NaYF4: Yb3+/Er3+ ultrasmall upconverting nanoparticles (US- UCNPs; sub-5nm) at room temperature. These US-UCNPs were prepared following thermal decomposition procedure. The generation of fourth order harmonic peak (FHG) and fifth order harmonic peak (FIHG) are distinguished under fs- pulse excitation, concurrently. Further, the precisely synthesized US-UCNPs exhibit strong blue emissions under 900 nm continuous wave (CW) laser-diode excitation. A significant red shifting is explored with 950-990 nm tunable laser sources.