The effect of repeated radiative energy transfer on the observed excited-state lifetime τ<sub>obs</sub> of a luminescent species in a solid is studied by Monte Carlo simulations. Increasing the sample path length, the reabsorption coefficient, or the luminescence quantum yield significantly lengthens τ<sub>obs</sub> relative to its intrinsic value τ<sub>0</sub>. This effect is additionally amplified by total internal reflection. Room-temperature lifetimes of <sup>2</sup>F<sub>5/2</sub> in YAG:1%Yb<sup>3+</sup> and <sup>4</sup>I<sub>11/2</sub> in YLF:5%Er<sup>3+</sup> were measured in a spherically refractive-index-matched geometry, yielding the low values of 0.9489±0.0006 and 3.75±0.01 ms, respectively. It is concluded that lifetimes obtained from non-refractive-index matched experiments are usually significantly overestimated. The technique presented is easily applicable to room-temperature excited-state lifetime measurements of many luminescent solids.
© 1997 Optical Society of America
Markus P. Hehlen, "Reabsorption artifacts in measured excited-state lifetimes of solids," J. Opt. Soc. Am. B 14, 1312-1318 (1997)