Color centers in KCN: a structural analysis of crystalline domains

Pure singlecrystals of KCN exposed to X-rays showed several color centers detected by EPR. The F center was identified through the correlation of its optical absorption band which satisfies the Ivey law for the KCN lattice parameter and the EPR spectrum typical of a center in an anionic site. Two other color centers were identified: N-2 and HCN-. Two centers assigned to hydrogen atoms have their models proposed: U2 and U3 centers. Two other centers remain unidentified: an anionic and an extrinsic centers. The orthorhombic character of the N-2 center EPR parameters allowed an structural analysis of the crystal line domains in the orthorhombic phase. The optical absorption spectrum of the HCN- center in KCl matrix was investigated and showed a set of resolved bands with a constant energy splitting; this splitting was associated to a vibrational mode of the excited state of this molecular ion. (author)