Paramagnetic resonance in irradiated Sr(NO3)2 single crystal

Paramagnetic resonance absorption of centres with spin 1/2 centered aboutg=2 is reported in gamma-irradiated single crystals of Sr(NO₃)₂. At room temperature four centres are detected which appear to exhibit axial symmetry about the 111] crystal direction. Two of the observed centres have a resolved hyperfine structure of N¹⁴. This hyperfine structure and axial symmetry of the centres indicate that they could be irradiation products of the nitrate ion. To find the number of trapped electrons, a simplified calculation of the molecular orbitals of planar and pyramidal NO₃ is carried out. Centres with a resolved hyperfine structure are then identified as pyramidal NO ₃ ^? and a NO₂ molecule rotating about the 111] direction. Two centres without hyperfine structure are not identified exactly.