Abstract

Recently 4fⁿ- 4f^n-1‘5d transitions of rare-earth (RE) ions in crystalline matrices have been studied extensively for potential application as tunable solid state lasers in the near-UV region. For this purpose, Ce³⁺ with the simplest configuration (f¹) has been unquestionably the most popular, however, other RE ions with several 4f electrons have been also investigated to explore the possibilities to extend the tunable range. In this context, Laroche et al. have measured the 4f² - 4f5d excited-state absorption (ESA) spectra of Pr³⁺ in LiYF₄, and analyzed the 4f5d energy levels of Pr³⁺ in LiYF₄ in detail based on the crystal field theory [1]. Although the crystal field theory is quite effective for identification of observed peaks, ah initio approach is still desirable for the theoretical prediction of spectral properties of hypothetical candidate materials especially for those involving 5d levels strongly interacting with crystalline environment. In the present work, we have developed a totally nonempirical relativistic configuration interaction (CI) computation code using a model cluster, and calculated the 4f² – 4f 5d ground-state absorption (GSA) and ESA spectra of Pr³⁺ in LiYF₄ without any empirical parameters.

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