Term of Award

Summer 2017

Degree Name

Master of Science in Applied Physical Science (M.S.)

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Chemistry

Committee Chair

Xiaojun Wang

Committee Member 1

Li Ma

Committee Member 2

Maxim Durach

Committee Member 3

John Stone

Committee Member 3 Email

jstone@georgiasouthern.edu

Abstract

In this work, the photothermal conversion of Au nanorods is studied, and the enhancement of red emission (4I9/2 to 4I15/2) of Er3+ in Gd1.4(WO4)3: Er0.63+ incorporating Au nanorods (Au@ Gd1.4(WO4)3: Er0.63+) has been observed in up- and down- converted emission and excitation processes. Different aspect ratios of Au nanorods ranging from 2.8-4.8, which correspond to longitudinal plasmon resonance bands from 665 to 850 nm, have been synthesized via a seeding method. Based on the fact that the aspect ratio of the nanorods can be tuned by H2O2 etching, the dynamic photothermal conversion of Au nanorods is recorded, and it has been found that the photothermal conversion gets stronger as the longitudinal plasmon resonance peak of nanorods approaches the wavelength of incident light. By incorporating the prepared Au nanorods with various aspect ratios, Au@Gd1.4(WO4)3: Er0.63+ is synthesized using a hydrothermal synthesis method. The phosphors are characterized by Scanning Electron Microscopy and X-ray Powder Diffractometry, and their particle size and crystal structure have been confirmed. Under similar synthesis conditions Au@Gd1.4(WO4)3: Er0.63+ particles show an average size less than 300 nm, smaller than the size of the Gd1.4(WO4)3: Er0.63+ phosphor without Au nanorods. Under near infrared excitation, the up-converted red emission at 655 nm is enhanced and the maximum enhancement is found when the Au nanorods have the lowest resonance absorption, at 665 nm. Also, under ultraviolet excitation around 300 nm, the down-converted red emission at 655 nm has been significantly enhanced through the charge transfer process. The dynamics processes of excitation and the mechanism of the enhancement is discussed.

Research Data and Supplementary Material

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