Intersubband infrared absorption in a GaAs/Al0.3Ga0.7As quantum well structure Investigation on the quantum well structure of a GaAs/Al0.3Ga0.7As superlattice grown on a misoriented substrate
The stepwise conversion of infrared (=0.97 p) radiation to near infrared {0. 81 p) and visible (0.475 p) light in YF3 sensitized with Yb ' and activated with Tm ' has been studied in detail. The lifetimes and fluorescence intensities of the important manifolds (Yb I"&~2, Tm 3H4, Tm E4, and Tm G4), as we11 as the Yb-to-Tm transfer probability coefficients for the three steps of the process, have been measured as functions of concentration. A saturation effect previously observed in the Tm emission versus infrared excitation intensity has been shown to result from the rate of depopulation of Tm H4 by the second Yb-to-Tm transfer exceeding the Tm H4 decay rate. This was used to determine the second transfer probability coefficient.The first transfer probability coefficient was found to be 1.2&&10 ' cm sec independent of Tm concentration and for Yb concentration of the order of 10 at. /o and greater. The second transfer probability coefficient was found to be approximately 10 4 cm sec for Yb concentrations of 25 at. % and greater. The third transfer probability coefficient was found to be 2. 7x10 cm sec . The dependence on Yb concentration of the relative efficiency of conversion to 0.475p light agrees well with the values calculated from a rate-equation model using the measured lifetimes and transfer probability coefficients.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.