Abstract
The HCN- molecular ion was produced in single crystals of KCN: 10-2 OH- irradiated by UV light at 77K. The spin-Hamiltonian parameters were measured at 60K and the temperature dependence of the spectrum was investigated between 60 and 170K. This temperature dependance is explained by the rapid motion of the molecule with the increasing temperature and the elastic interaction of the molecule with the surrounding ions. Using the similarity between the paramagnetic HCN- molecule and the CN- ions of the host lattice a qualitative picture of the local phenomena occurring in the ferroelastic phase of KCN could be made and the energy of the elastic interaction between CN- ions was estimated to be of the order of 7 meV.