[Spin glass type structures in chloroplasts]

The nature of discovered in [2] magnetic anisotropy of ESR signal with g approximately 3 appearing in chloroplasts at helium temperatures has been studied and clarified. It was found that a signal with these properties can arise only when dark adapted chloroplasts are cooled down to temperatures lower than 23 K in an external magnetic field (Ho greater than 2.300 Oe). The results obtained indicate that the system studied belongs to the type of "spin glasses", i. e., of the magnetically diluted structures with cooperative magnetic interaction between centres. These cooperative properties can be most distinctly observed at definite temperature and magnetic field strength values.