Mössbauer Effect ofFe37in a Cobalt Single Crystal

The Mössbauer effect of ${\mathrm{Fe}}^{57}$ in a single crystal of cobalt has been observed. The quadrupole coupling $e^2\mathrm{Qq}$ was measured to be -0.064 mm/sec, and the hyperfine field was found to be isotropic and equal to -316.6±2.5 G. The significance of these results is discussed in relation to the theory of hyperfine fields in metals. The ratio of the magnetic moments of the excited and ground states of ${\mathrm{Fe}}^{57}$ was measured to be 1.7135±0.0015.