Discipline: Physics
Subcategory: Nanoscience
Deonte' Alexander - Dillard University
Co-Author(s): Abdalla M. Darwish, Allan Burkett, Ashley Blackwell, and Keylantra Taylor, Dillard University, New Orleans, LA Sergey Sarkisov, SSS Optical Technologies, Huntsville, AL Darayas Patel, Oakwood University, Huntsville, AL Brent Koplitz, Tulane University, New Orleans, LA David Hui, University of New Orleans, New Orleans, LA
The work was 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 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 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 C. The fabricated nanocomposite films were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and optical fluorescence spectroscopy. 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. The proposed method can be potentially used for making a wide variety of nano-composite films.
Funder Acknowledgement(s): The authors would like to acknowledge the support from DoD AFOSR grants FA 9550-12-10068, W911NF-11-1-0192 and NSF/LA BOR DU LS-LAMP grants.
Faculty Advisor: Abdalla Darwish,