title: Improved ultraviolet upconversion emissions of Ho3+ in hexagonal NaYF4 microcrystals under 980 nm excitation.
abstract: Under 980 nm excitation, enhanced ultraviolet (UV) upconversion (UC) emissions at 242.4 nm, 276.1 nm, 289.7 nm, 296.4 nm, 303.6 nm, 357.7 nm and 387.8 nm of Ho3+ ions were observed in beta-NaYF4:20%Yb3+, 1.5%Ho3+ microcrystals (MC) which were synthesized through a hydrothermal method. The results indicated that these UV emissions came from five- and four-photon UC processes. Dynamical analysis on Ho3+ excited states suggests that, for excited Ho3+ ions, the higher the energy level is, the shorter the lifetime is.
authors.forename: Lili
authors.initials: L
authors.lastname: Wang
authors.forename: Weiping
authors.initials: W
authors.lastname: Qin
authors.forename: Min
authors.initials: M
authors.lastname: Lan
authors.forename: Lanlan
authors.initials: L
authors.lastname: Sun
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Liu
authors.forename: Dan
authors.initials: D
authors.lastname: Zhao
authors.forename: Guanshi
authors.initials: G
authors.lastname: Qin
authors.forename: Changfeng
authors.initials: C
authors.lastname: Wu
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Chuai
authors.forename: Weihua
authors.initials: W
authors.lastname: Di
authors.forename: Chunfeng
authors.initials: C
authors.lastname: He