Beta decay of 99Tc/sup m/

The emission of β rays from 6.02-h 99Tc/sup m/ has been detected with an intermediate-image magnetic spectrometer. β-ray components with end-point energies of 434.8 +- 2.6 keV (β0) to the 99Ru ground state and 346.7 +- 2.0 keV (β1) to the 90-keV state were found with intensities per decay of (1.0 +- 0.3) x 10-5 for β0 and (2.6 +- 0.5) x 10-5 for β1. In the Kurie plot analysis the unique first-forbidden ''α'' shape was assumed for β0 and an allowed shape was assumed for β1. Values of log f1t=9.39 +- 0.11 for β0 and log f0t=8.66 +- 0.08 for β1 were derived. γ rays of 322, 233, and 140 keV were observed in a calibrated Ge(Li) detector with relative source intensities of I322:I233:I140= (1.13 +- 0.09) x 10-6:(0.95 +- 0.17) x 10-7:1.000. The total β-ray branching of 3.7 x 10-5 results in a negligible correction to dosage calculations in the use of 99Tc/sup m/ for diagnostic nuclear medicine