title: Upconversion emissions from high-energy states of Eu3+ sensitized by Yb3+ and Ho3+ in β-NaYF4 microcrystals under 980 nm excitation.
abstract: Under 980 nm excitation, multiple ultraviolet and visible upconversion luminescence from Ho3+ and Eu3+ ions were observed in Yb3+/Ho3+/Eu3+ tri-doped NaYF4 microcrystals (MCs). The high-energy states (5H3-7, 5L6, 5D3 and 5D2) of Eu3+ ions could be efficiently populated by two-step energy transfer (ET) processes of Yb → Ho → Eu. Four-, three-, two-photon UC processes of Eu3+ ions were confirmed by the dependence of 5H3-7, 5L6 and 5D0 levels emission intensities on the pumping power.
authors.forename: Lili
authors.initials: L
authors.lastname: Wang
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Liu
authors.forename: Zhe
authors.initials: Z
authors.lastname: Chen
authors.forename: Dan
authors.initials: D
authors.lastname: Zhao
authors.forename: Guanshi
authors.initials: G
authors.lastname: Qin
authors.forename: Weiping
authors.initials: W
authors.lastname: Qin
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D007834:Lasers; D008163:Luminescent Measurements / Q000295:instrumentation*; D055096:Optical Devices