Abstract
The photoelectron paramagnetic resonance (photo‐EPR) technique is applied to studies of photoionization transitions of chromium impurities in ZnS and GaAs lattices. The different dynamic photo‐EPR experiments are discussed enabling an unambiguous interpretation of the nature of photoionization transitions to be made and a determination of the chromium centers ionization energies (Eopt, Eth, Erel) to be carried out.