EPR Studies of Copper-Doped L-Alanine Crystals: Ultraviolet-Induced Conversion in Cu2+ Complexes

Publisher Website
Google Scholar
Abstract
Copper‐doped L‐alanine crystals exhibit an absorption band in the ultraviolet region. EPR observations indicate that as a result of this uv absorption, multiple conversion takes place in the Cu2+ complexes. In addition to the complexes originally formed by the impurity ions, two others were identified during uv irradiation at 77°K. These were distinguished by their tensor parameters and thermal stabilities, as well as an absence of ligand nitrogen hyperfine structures. The EPR spectra also indicated the formation of free radicals which, however, were not positively identified. On increasing the temperature, these underwent an irreversible transformation accompanied by the formation of yet another copper complex showing a quintet ligand hyperfine structure of 1:2:3:2:1 intensity ratio.