Deonte Alexander - Dillard University
Co-Author(s): Abdalla M. Darwish, Physics Department, Dillard University, New Orleans, LA
This work is to investigate the possibility of making polymer–inorganic nano-composite films with upconversion fluorescence properties using the double beam matrix-assisted pulsed laser evaporation (DB-MAPLE) method. The conventional method of pulsed laser deposition only uses one laser to ablate a single target. Which limits the viariety of nano-composite thin films. The existing pulsed laser deposition vacuum chamber was modified to accommodate two laser beams of different wavelengths for simultaneous ablation of two separate targets: a polymer host and a rare earth containing rare earth ion enriched upconversion fluoride dopant. The polymer target was prepared in chlorobenzene and kept frozen during the ablation with circulating liquid nitrogen in accordance with the MAPLE procedure. It was ablated with 1064 nm beam from a pulsed Nd:YAG laser. The upconversion pellets made of the synthesized powders of inorganic phosphors of NaYF4:Yb3⁺, Er3⁺ and NaYF4:Yb3⁺, Ho3⁺were ablated with 532-nm beam from the same laser. The plumes from both targets were kept overlapping on the substrate during the deposition. X-ray diffraction analysis revealed that the most favorable for upconversion emission of the inorganic target materials was the hexagonal, beta phase of the NaYF4 matrix existing at a baking temperature between 400℃ and 600℃. The fabricated nanocomposite films were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and optical fluorescence spectroscopy. It is observed that, the polymer nano-composite films generally retained the crystalline structure and the upconversion fluorescence properties of the initial rare earth compounds due to better control of the deposition process of the materials with substantially different properties. It’s proved that, the proposed method can be potentially used for making a wide variety of nano-composite films. Which can not be done by the conventional pulsed laser deposition. Future research involves the use of the nano-composite thin films to detect hazardous chemicals.
Funder Acknowledgement(s): Army Grant, Air Force AFOSR Grant, U.S. Department of Defense, NSF/LA; DU LS LAMP Grants, and NASA NORC CAN Program.
Faculty Advisor: Abdalla Darwish, email@example.com
Role: I have done all parts of the MAPLE procedure.