Characterization of lunar ferromagnetic phases by the effective linewidth method

The effective linewidth technique, first developed to study the physics of microwave relaxation in ferrites, has been successfully applied to lunar matter. Effective linewidth measurements have been made on two selected samples containing disperse spherical metallic iron particles below 40μm in diam. The data were obtained for fields from 7 to 12 kOe and a temperature range 125 - 300 K. The effective linewidth was field independent and temperature independent at 650 - 750 oe. The high field tails of the ferromagnetic resonance absorption were highly Lorentzian. From the relatively large and temperature independent high field effective linewidths, it appears that (1) the metallic iron phases in lunar soil are rather impure, (2) the impurities are passive, in that there is no evidence for a temperature peak process, and (3) these samples contain no appreciable magnetite.