Colloquium: Photoluminescence Spectra of Emeralds from Different Origins

Date: 
03/25/2016 - 3:30pm to 4:30pm
Location: 
CP155
Speaker(s) / Presenter(s): 
Dr. David Thompson (University of North Alabama)
Type of Event (for grouping events):
Trace impurity ions Cr3+ and V3+ in emerald both absorb visible light in the red and blue-violet range, giving rise to the emerald's green color. The Cr3+ impurity can also luminesce in the visible red when illuminated with laser light. We have shown that peak positions and relative intensities of R lines appearing in the photoluminescence spectrum of emerald depend upon the emerald's origin. In particular the R1 line of lab created emeralds is positioned at the shortest wavelengths, while for natural emeralds with a non-schist origin this line is found at the same or longer wavelengths, and for natural schist origin emeralds this line peaks at even longer wavelengths.1 Recently we have learned that the R1 line's peak position depends upon concentrations of trace impurities Mg2+ and Na+ in the emerald, and that the less common shifts of the R2 line's peak arise from increased concentrations of the trace impurity Li1+.

 

Refreshments will be served in CP 179 at 3:15 PM