An ozonide ion is detected in single crystals of KI by means of electr
on paramagnetic resonance. The new data support the monovacancy model
for the location of the 0- ion in the alkali halides proposed recently
. Theoretical calculations using self-consistent field Hartree-Fock me
thods are performed in order to determine the principal g-tensor value
s for the O3- molecular ion. The results are in good agreement with th
e experimental data.