Blue upconversion emission of Cu2+ ions sensitized by Yb3+-trimers in CaF2

摘要

Under 978 nm near-infrared (NIR) excitation, blue upconversion (UC) emissions from CaF2:Cu2+, Yb3+ were first observed at similar to 420 nm. It was ascribed to the 3d(8)4s(1) -> 3d(9) transition of Cu2+ ions. From transient measurements, the UC process was found to be dominated by the energy transfer process in which three excited Yb3+ ions simultaneously transfer their energy to one Cu2+ ion. The influence of Cu2+ concentration and temperature on the UC emission as well as the Jahn-Teller effect was also investigated.