Hyperfine interaction of13O and23Mg implanted in Pt

The spin relaxation timeT1 for short-lived beta emitters13O and23Mg implanted in Pt have been measured for the first time;T1T13O) = 2.90 ±0.65 Ks andT1T(23Mg) = 1665 ±140 Ks. The Knight shift for13O in Pt was measured at 300 K to beK(13O) = +(4.23 ±0.14) × 10−3. In the case of13O, the Knight shift is unusually large and the relaxation time is unusually fast compared with other interstitial impurities in Pt. A KKR band-structure calculation reproduces the present large Knight shift fairly well.