A new technique of the excited-state photoionization studies in Ce:LiYF 4 and Ce:LiLuF 4 crystals of the activator ions fluorescence decay is proposed. The excited-state photoionization spectra from 5
d-state of Ce
Regular frames and particle’s rotation near a black hole hole. In our previous work (
Pavlov and Zaslavskii in Gen Relativ Gravit 50:14, 2018. arXiv:1707