Cooperative Energy Transfer between Two Neighboring Eu3+ Ions and Energy Transfers from Eu2+ to Eu3+ and from Eu3+ to Yb3+ in Crystals for Quantum Cutting

Abstract

Energy transfer between Eu2+ and Eu3+ ions is examined in CaF2 crystal at not only room temperature but also 12 K. Energy transfer from Eu2+ to Eu3+ is confirmed. The reverse energy transfer from Eu3+ to Eu2+, however, is confirmed to be undetectable. Cooperative energy transfer between two neighboring Eu3+ ions in Eu3+-doped LiYb1−xEux(MoO4)2 crystal, which is combined with Eu-O charge transfer complex resonantly, is found to be responsible for the 1000 nm near infrared broadband emission from Yb3+ ions through the quantum cutting from the 5D2 excited state of Eu3+.