Steady-state luminescence measurement for qualitative identification of rare earth ions in minerals

Abstract

Minerals are the source of rare earth elements (REE), and knowledge of the amount of REE in different minerals is necessary for a mineralogist. We propose steady-state luminescence measurement as a quick and non-destructive method for detecting several lanthanide ions present together in the same sample. By using excitation and emission spectra of each 4f ion, rare earth ions could be easily identified. The most intense emission lines in the UV-VIS range are 336 nm for Ce³⁺, 420 nm for Eu²⁺, 596-649 nm for Pr³⁺ and Sm³⁺, 614-617 nm for Eu³⁺, at 478 and 573-579 nm for Dy³⁺, and 520-550 nm for Er³⁺ and Ho³⁺ ions. We have verified that the best excitation wavelength for each ion as follows: for Ce³⁺ and Eu²⁺, 295 nm and 336 nm; for Pr³⁺, 442 nm; for Sm³⁺, 399-408 nm; for Eu³⁺, 393-395 nm; for Dy³⁺, 348 nm; for Er³⁺, 377 nm; and for Ho³⁺, 415 nm.