Experimental upper limit to the time of nonradiative relaxation between4T2and2Estates in ruby

An upper limit of
5 \times 10^{-10}
seconds has been determined to the time of nonradiative relaxation between
⁴
T
2
and
²
E
states of ruby. The value was inferred from slope comparison of the experimental and theoretical rise curves of
R
-line fluorescence.