Project Description and History

While at the 1993 International Conference on Luminescence in Storrs , Connecticut , Ann and Dan heard a talk about sol-gel synthesis of rare earth-doped glass.  We thought it sounded like fun - something that could be done at Hamilton and Davidson. Since the summer of 1997, we've been working with Karen Brewer in the Chemistry Department at Hamilton on making glass and doing interesting spectroscopy on our own materials. One of the intriguing aspects is that our students make the samples.  They can decide what parameters they want to vary and then can create those samples.  We've had grants from the Research Corporation, the American Chemical Society and the National Science Foundation to support the project.  There have been many students who have made valuable contributions to the work and they are listed below. In the summer of 2003, Ann and Dan presented two posters of RE-based sol-gels at the Dynamic Processes Conference in Christchurch , NZ and two papers based on this work were published in the Journal of Luminescence.  At the 2006 March Meeting of the American Physical Society, Greg Armstrong presented the talk "Enhanced fluorescence in rare earth doped sol-gel glasses containing Al³⁺."  In the November issue of the Journal of Luminescence, our latest findings will appear.  The publications, posters and presentations listed on the other pages are based on the research we have done with our students.

We have observed fluorescence from many of the lanthanide rare earth ions.  Most recently, we've found the optical behavior of the rare earth ion Tb³⁺ in sol-gel glasses to be particularly useful.  By comparing the fluorescence from the ⁵D₃ and ⁵D₄ levels to the ground state, we have been able to learn a lot about the energy transfer among rare earth ions and between rare earth ions and the glass matrix.  Greg Armstrong began the work with a study of the variation in intensity of ⁵D₃ emission with annealing conditions.  In the summer of 2005, Yubo Lu '07 and Dan Campbell '08 of Hamilton College , and Rob Correll and Colleen Gillespie of Davidson continued the work with Tb³⁺ by studying the aging of sol-gel samples after annealing. During the academic year '05-'06 we continued to find new information that helps clarify the role of Al³⁺ as a co-dopant in the gels.  Al³⁺ increases the fluorescence yield significantly but how it does it is still not clear.  This topic continued to be the main focus for the summer of 2006.   There were four students working at the two schools and, in July, Dr. Kurt Hoffman from Whitman College and two of his students traveled to Davidson to join in the research effort, thanks to support from the American Chemical Society Petroleum Research Foundation. Silversmith and Thao Nguyen came for two weeks during July as well.  The outcome of that summer's work opened up many avenues.  Carlos Ortiz '07 of Davidson College investigated upconversion in thulium using pulsed laser excitation.  The whole group looked at the nonexponential behavior of the ⁵D₃ emission of Tb³⁺ due to cross relaxation in order to learn more about the rare earth local environment.  DPC 2007 was held in Segovia, Spain in June of 2007.  It was attended by Boye, Silversmith, Hoffman, and Nguyen who presented 3 posters and an oral presentations.  Three manuscripts were submitted and all were accepted for publication in the Journal of Luminescence.

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