Study of the d-f Emission,and f-d Ground-State and Excited-State Absorption of Nd3+ in Crystals Using the Simple Model

The simplified model for 4f-5d transitions is applied to obtain the line strengths for emission, ground-state absorption and excited states absorption involving 4f-5d transitions of Nd³⁺ in crystals. The results are host independent for the usual case where 5d crystal-field interaction can be considered as strong, in the sense that the calculated 5d-4f emission relative line strengths will be the same for Nd³⁺ in any host. Also the calculated 4f-5d absorption line strengths can be grouped by the 5d crystal-field components. For each 5d crystal-field component, the group of absorption line strengths for different 4f²5d transition final states forms a pattern independent of the 5d crystal-field component and the host. For practical cases, due to strong but still limited 5d crystal-field splitting, the transitions to different 5d crystal-field components may overlap each other. The theoretical results are used to interpret available experimental data.