Local symmetry distortions during f-f transitions in HoAl3(BO3)4 single crystal
https://doi.org/10.1016/j.optmat.2024.116247
The polarized absorption spectra of the HoAl3(BO3)4 single crystal were studied in the region of f–f transitions 5I8→5F5, 5S2 + 5F4, 5F3 and 5F2 inside the 4f shell of the holmium ion as a function of temperature in the range of 5–90 K. In a number of absorption lines the splitting which are not provided by the local point group D3 symmetry of holmium ion in the crystal are found. This phenomenon is explained by local changes in the structure in both the excited and ground states of holmium under the influence of a perturbation caused by a photon. This perturbation mixes the ground and excited states and changes the interaction of the atom with its environment. It was also shown that the magnitude of the splitting depends on the polarization of the incident light and on the temperature of the sample.