Nuclear magnetic resonance on oriented nuclei in a paramagnetic crystal, 52Mn and 54Mn in La2Mg3(NO3)12.24H2O
1970; Elsevier BV; Volume: 50; Issue: 2 Linguagem: Inglês
10.1016/0031-8914(70)90006-6
ISSN1873-1767
Autores Tópico(s)Electron Spin Resonance Studies
ResumoTransitions between hyperfine-structure levels of oriented 52Mn and 54Mn ions included in lanthanum magnesium nitrate were induced by radiofrequency irradiation. The Mn ions were oriented by cross relaxation with Ce ions, partly replacing the La ions (Ce: La=1: 103). Changes in the directional anisotropy of the gamma rays emitted by the nuclear spin system were utilized to detect the rf resonance transitions. Different hfs transitions could be induced separately. Complete saturation of each transition was accomplished by slowly sweeping the frequency of the rf field across the resonance, the rf field amplitude being as low as 10-4Oe. A theoretical description of the process is given in which the enhancement of the rf amplitude at the position of the nucleus through the intermediary of the electronic spin plays a major role. The agreement with the experimental results is satisfactory. The observed resonance lines were very narrow; their width was mainly determined by the inhomogeneity of the external magnetic field. Also a homogenous linewidth was shown to be present; it is argued that it originates from the protons surrounding the Mn ions. By taking data at various field strengths and directions very accurate values of the hfs parameters were obtained. By comparing these with the data on the stable isotope 55Mn the magnetic moments of 52Mn and 54Mn were derived with a precision determined only by the error in the value of the magnetic moment of 55Mn. The quadrupole moments of both radioactive isotopes were determined for the first time.
Referência(s)