Infrared-to-Visible Upconversion in Rare Earth Doped Materials

Author

Deon G. Ettinger

Publication Date

7-15-1977

Abstract

Upconversion materials have been prepared which may be stimulated by incident 970 nm radiation to emit in the visible region. The couples Yb⁺³-Ho⁺³ in a YF₃ host and Yb⁺³-Er⁺³ in YF₃, YPO₄, Li₃PO₄ and Y₂O₂S hosts have been studied at temperatures from 9K to 273K. For (Y_.80Yb_.19Er_.01)F₃ emission bands at 657 nm, 538 nm, 520 nm, 409 nm and 379 nm have been detected and determined to result from 3-, 2-, 2-, 3-, and 3-photon absorption processes respectively. The other materials doped with Yb⁺³ and Er⁺³ showed similar behavior butmuch reduced emission intensities. (Y_.80Yb_.19Ho_.01)F emission bands at 746 nm, 645 nm, 544 nm and 489 nm, all resulting from 2-photon absorption processes, were detected. For the most part, the mechanisms which have been proposed in the past to account for upconversion in Ho⁺³ doped materials do not adequately explain the experimental results. This arises from the commonly held, but incorrect, belief that the behavior of Ho⁺³ activated systems was similar to that of Er⁺³ activated systems. In particular the important assumption that the temperature dependence of visible emission in Ho⁺³ activated upconvertors is the same as that for Er⁺³ activated upconvertors has been shown to be incorrect. The Er⁺³ emission intensity decreases while the Ho⁺³ emission intensity increases as the temperature is lowered from 140K to 9K. The significance of this phenomenon is discussed. Overall suggestions for upconvertor improvements and further experimental studies are made as well. In the course of this experimental work a computer controlled photon counting spectrophotometer was designed and constructed. Preliminary optimization studies indicated that the system was a powerful data acquisition package but that further studies were needed to determine what the most critical parameters for control and optimization might be.

Language

English

Document Type

Dissertation

Degree Name

Chemistry

Level of Degree

Doctoral

Department Name

Department of Chemistry and Chemical Biology

First Committee Member (Chair)

Thomas Michael Niemczyk

Second Committee Member

Robert Edwin Tapscott

Third Committee Member

William Fletcher Coleman

Fourth Committee Member

Edward A. Walters

Recommended Citation

Ettinger, Deon G.. "Infrared-to-Visible Upconversion in Rare Earth Doped Materials." (1977). https://digitalrepository.unm.edu/chem_etds/239