Figure shows absorption spectra of YScO3 crystal fiber doped with Yb 3+ ions being measured at temperatures of 300 K and 77 K. The decrease in temperature from 300K to 77K results in narrowing of the absorption bands of Yb 3+ ions, their structuring, and the emergence of new lines that were not visible at the higher temperature (300 K). Surprisingly, the number observed absorption lines (six ones) exceeds the expected number of three lines. This suggests the presence of additional Yb 3+ optical centers within the crystal matrix, which contribute to the observed spectral overlap and the splitting and population of Stark components in the 2 F7/2 ground state. The existence of distinct optical centers of Yb 3+ ions in other crystals like Y2O3 and Sc2O3 has been previously observed in .