Abstract
The ultraviolet-absorption spectra of europium and ytterbium ions in Ca crystals have been measured at room and liquid-nitrogen temperatures. Their spectra are similar to each other in the general location of their absorption bands. Both spectra consist of: (i) bands, between about 24 000 and about 50 000 , due to isolated R with crystal field strength ∼17 000 between and bands; (ii) bands, shifted ∼9 000 to higher energy, due to R ions surrounded by R neighbors; (iii) a broad and weak band of in Ca with maximum at ∼71 000 ; and (iv) bands above ∼64 000 due to isolated R and cluster-ion R. The structure in the absorption spectra of both isolated and ions can be interpreted as formed through interaction between a electron having or crystal field symmetry and electrons in the ground multiplet of the core.
- Received 3 February 1969
DOI:https://doi.org/10.1103/PhysRev.184.348
©1969 American Physical Society