ESR and Optical Absorption Studies of ClO<inf>3</inf> in Ba(ClO<inf>4</inf>)<inf>2</inf> · 3H<inf>2</inf>O Single Crystals

The ClO3 radical observed in γ‐irradiated Ba(ClO4)2 · 3 H2O is studied by ESR and optical absorption techniques. The radical orientation and stability with increased irradiation and thermal and UV light bleaching are discussed. A temperature variation study by ESR reveals that there is an increase of 13.8% and a decrease of 4% in the chlorine p‐orbital and s‐orbital spin densities, respectively, when the temperature is lowered from 300 to 77 K. A comparison of the results obtained for ClO3 with the other iso‐electronic trioxide radicals shows that the maximum fractional change in the spin densities occurs in the case of ClO3 and that these changes depend on the electronegativity of the central atom. Copyright © 1982 WILEY‐VCH Verlag GmbH & Co. KGaA