Absorption, Fluorescence, and Energy Levels of Ho3+ in Hexagonal LaCl3

Abstract

The absorption and fluorescence spectrum of Ho³⁺ in LaCl₃ has been obtained between 2600 and 12 000 Å and the energy levels established. The Stark components are virtually complete, except for the high‐lying levels where, because of crowding and weak absorption, the interpretation becomes uncertain. The observed crystal field splittings for the low‐lying levels agree reasonably well with calculated ones if B₂⁰=122, B₄⁰=—45, B₆⁰=—28, B₆⁶=280 cm^—1. Zeeman effects for fields parallel and perpendicular to the axis have been obtained and used for the classification. Approximately 180 absorption and 380 fluorescence lines have been obtained. A considerable number of the former show resolved nuclear hyperfine structure. The mechanism for energy transfer between excited states has been cleared up.