Photoconductivity and optical quenching of the photoconductivity were measured. The photoneutralization of the Fe 3 + centres has been found to occur for photon energies down to 0.8 eV (i.e. the threshold can not be at 1.1 eV, as often quoted). The conclusion from our previous paper that the lattice relaxation energy is small, has been confirmed. It has to be smaller than 0.1 eV.PACS numbers: 71.55. Gs, 72.40.+w In ZnSe:Fe iron atoms substitute zinc and (speaking in the ionic language) in the Fee+ charge state they are neutral with respect to the lattice. The presence of the Fe3 + ( ionized) centres results from the compensation by shallow acceptors.In our previous paper on the iron centres in ZnSe [1] we have described the first observation of the photoionization of the Fee+ centres:and we have determined the optical ionization energy of the Fee+ centres at 77 K-2.1 eV ± 0.1 eV. As the thermal activation energy of the valence band -iron level transitions was found in the Hall effect measurements [2] to be 0.62 eV, and the energy gap at 77 K is 2.81 eV, we concluded that the lattice relaxation energy is small and the Fe2 +/3 + donor level in ZnSe is at 77 K both optically and thermally about 2.1 eV below the conduction band.(337)

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