Hyperfine Structure of Technetium-99 from Paramagnetic Resonance

Abstract

The hyperfine structure of tetravalent ${\mathrm{Tc}}^{99}$ in a single crystal of ${\mathrm{K}}_2$Pt${\mathrm{Cl}}_6$ was detected at 1.25 cm wave-length and at the temperature of the boiling point of liquid helium. The significant parameters are: $g=1.9896\mathrm{}\pm 0.0005$, $A_{max}=148.8\mathrm{}\pm 0.4$ gauss, $A_{min}=144.0\mathrm{}\pm 0.4$ gauss. The nuclear spin is confirmed as $\frac{9}{2}$. An additional six isotropic lines with $g=2.050\mathrm{}\pm 0.005$ and $A=109\mathrm{}\pm 3$ gauss are found at liquid nitrogen temperature. These hyperfine lines may possibly be due to the rhenium isotopes 185 and 187 with nuclear spins $\frac{5}{2}$.