고분해 레이저 분광학에 의한 CeF₃:Eu^(3+)의 형광 특성 연구

Abstract

Luminescence properties of CeF₃:Eu^(3+) are investigated by high-resolution laser-excitation spectroscopy. More than five lines corresponding to the different crystallographic sites for Eu^(3+) are observed in the excitation spectra of ^(7)F_(0) → ^(5)D_(0) transition at 12 K. The sharp lines at 577.6 (A), 577.9 (B), 575.3 (C), 579.1 (D), 579.4 (E) show quite different behavior in comparison with the broad band in the wavelength range of 574 ～ 586 nm (F band). Upconversion emissions in the wavelength ranges of 426 ～ 452 nm and 340 ～ 390 nm are observed as the five sites (A to E) are selectively excited, while no upconversion emission was observed for the site with broad F band. The results indicate that the sites A to E are attributed to the isolated Eu^(3+) with different crystallographic symmetries situated near the Eu^(3+) clusters and the site F with broad band are due to the Eu^(3+) clusters. The pump photon energy of the upconversion excitation matches with the transitions ^(7)F_(0) → ^(5)D_(0) → ^(5)I_(5). The ions in the 5I5 state relax nonradiatively in cascade to the lower levels causing ^(5)H₃and ^(5)D₃levels to emit. The origin of different crystallographic sites and upconversion mechanism of Eu^(3+) in CeF₃. are discussed in detail.