EFFECTS OF HIGH ENERGY ELECTRON IRRADIATION ON SINGLE CRYSTALS OF AMMONIUM AND SODIUM BIFLUORIDE,
Abstract
Radiation effects in single crystals of ammonium bifluoride and sodium bifluoride were studied by electron spin resonance and optical methods following 1-MeV electron irradiations at 77K. The irradiations changed the samples from clear to deep blue-green and both crystal types showed paramagnetic resonances which were determined to result from F2(-) ions in anion sites. This defect resulted from the displacement of hydrogen atoms from their normal positions in the linear bifluoride (FHF) (-) ions. Only in NH4HF2 were the displaced hydrogen atoms detected. Best-fit spin-Hamiltonian parameters for the F2(-) ahd H defects are given. Optical absorption measurements on the irradiated bifluorides are discussed. The ESR annealing characteristics for the F2(-) ions in both crystals appear to follow second-order kinetics. In two of the three inequivalent sites for F2(-) ions in NH4HF2 the orientation of the F2(-) molecular axis differs by eight degrees from the reported crystallographic axis of the corresponding bifluoride anion. This is interpreted to result from weaker hydrogen bonding between nitrogen and fluorine for the F2(-) ion than for the bifluoride ion in ammonium bifluoride, because of an increased N-H-F distance for the shorter F2(-) ions. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1970
- Accession Number
- AD0712321
Entities
People
- Lawrence J. Vande Kieft
Organizations
- Ballistic Research Laboratory