Hyperfine Interactions ofFe57inFe3C

The absence of the quadrupole interaction from the room-temperature spectrum of ${\mathrm{Fe}}_3$C is shown to be only apparent. The spectrum was unfolded into two components in accordance with the two known structural sites, $G$ (general) and $S$ (special). The electric field gradient is found to be axially symmetric at each site. The quadrupole interaction is found to be 0.32 mm/sec for the $G$ site and - 0.58 mm/sec for the less-symmetric $S$ site. The angles $\theta$ between the magnetic field $\overrightarrow{\mathrm{H}}$ and the electric field gradient $V_{\mathrm{zz}}$ were found to be 50° and -50° for $G$ and $S$, respectively. The hyperfine fields are found to be $H_G=205\mathrm{}$ kOe and $H_S=207\mathrm{}$ kOe. No difference in the isomer shift could be observed. The only indications of two sites in the room-temperature spectrum are the broadening (and therefore shortening) of the $+\frac{3}{2}\to +\frac{1}{2}$ transition line (sixth line), and a smaller broadening of the $-\frac{1}{2}\to -\frac{1}{2}$ transition line (second line).