Comparative Crystal‐Field Analyses of 4fN Energy Levels in LiYF4:Ln3+ Systems

Comparative analyses of the 4fN(Ln3+) energy level structures in a series of LiYF4:Ln3+ systems are reported. These analyses focus on empirical energy level data currently available in the literature for the Pr3+, Nd3+, Eu3+, Dy3+, Ho3+, Er3+, and Tm3+ systems, and they are based on the use of a phenomenological Hamiltonian that permits trans‐series comparisons of 4f‐electron/crystal‐field interactions. Spin‐correlated crystal‐field (SCCF) interactions are considered in the phenomenological energy level analyses of the Pr3+, Nd3+, Er3+, and Tm3+ systems. Differences between analyses carried out with and without inclusion of SCCF effects are most apparent for the Er3+ and Tm3+ systems. For these systems, inclusion of SCCF effects leads to significant improvement in agreement between calculated and observed crystal‐field splittings within certain multiplet manifolds. The calculated crystal‐field energy level structures within the 1G4 and 1D2 multiplets of Tm3+ and the lowest‐energy 2H11/2 multiplet of Er3+ exhibit particular sensitivity to the SCCF components of the model Hamiltonian. Comparisons between the present work and previously reported analyses of LiYF4:Ln3+ systems are presented.