ISSN:
1434-6036
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract In addition to Ni2+(3d 8) with its known internal transitions, Ni+(3d 9) is identified here by detecting its2E(D)↔2 T 2(D) transition in ZnS and ZnSe both in absorption and emission. An analysis of vibronic satellites in these spectra indicates a moderate Jahn-Teller coupling in the2 T 2 ground state. Thermal annealing procedures which raise the Fermi level allow to increase the intensity ratio between the characteristic low-temperature optical bands of Ni+ and Ni2+. Ionisation and capture processes at these centres are studied by using the intensity of internal transitions as a probe for the concentration of the respective charge state of nickel. They are induced by additional optical irradiation of the samples in various spectral ranges. These photoionisation and radiative recombination processes manifest themselves in absorption, excitation and luminescence spectra as well as in the spectral response of photosensitive EPR signals. In addition to the threshold for the process [Ni2+]x+hv→[Ni+]′+e vb / which had previously been determined, the experiments yield another threshold for the reaction [Ni+] +hv→[Ni2+]x+e cb /′ . A well-known but hitherto unsettled emission band of ZnS:Ni is attributed to the radiative recombination which is the reverse of this photoionisation. The corresponding transition in ZnSe:Ni is observed as well.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01304198
