Mössbauer Effect inTb159

The linewidth of the Mössbauer resonance of the 58-keV radiation from ${\mathrm{Tb}}^{159m}$ has been measured with ${\mathrm{Dy}}^{159}$(as ${\mathrm{Dy}}_2$ ${\mathrm{O}}_3$) and ${\mathrm{Gd}}^{159}$(as ${\mathrm{Gd}}_2$ ${\mathrm{O}}_3$) sources and ${\mathrm{Tb}}_4$ ${\mathrm{O}}_7$, Tb metal, and ${\mathrm{Tb}}_2$ ${\left(\mathrm{C}{\mathrm{O}}_3\right)}_3$ absorbers, all at 80°K. The measured linewidths, extrapolated to zero absorber thickness, are 5.0±1.4 cm ${\sec }^{-1\mathrm{}}$ for the ${\mathrm{Dy}}_2$ ${\mathrm{O}}_3$-${\mathrm{Tb}}_4$ ${\mathrm{O}}_7$ system, 7.9±1.8 cm ${\sec }^{-1\mathrm{}}$ for the ${\mathrm{Dy}}_2$ ${\mathrm{O}}_3$-${\mathrm{Tb}}_2$ ${\left(\mathrm{C}{\mathrm{O}}_3\right)}_3$ system, and 11.5±1.0 cm ${\sec }^{-1\mathrm{}}$ for a 22 mg ${\mathrm{cm}}^{-2\mathrm{}}$ Tb metallic absorber. A few measurements with a ${\mathrm{Gd}}_2$ ${\mathrm{O}}_3$-${\mathrm{Tb}}_4$ ${\mathrm{O}}_7$ system gave 10.1±1.0 cm ${\sec }^{-1\mathrm{}}$ for a 27 mg ${\mathrm{cm}}^{-2\mathrm{}}$ ${\mathrm{Tb}}_4$