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Abstract

The internal conversion electron spectrum of transitions in the decays of the (86 min) 197mPt and the (18 h) 197Pt have been studied by means of an iron-free, double focussing beta-ray spectrometer. Conversion electrons were observed for transitions of 268.2 ± 0.2 and 269.1 ± 0.2 keV, the first ascribed to the decay of (18 h) 197Pt while the second ascribed to the decay of (86 min) 197mPt. An energy level in 197Au at 548 keV has also been observed for the first time from the decay of 197mPt, de-excited by the 269–279 keV cascade and a direct 548.4 ± 0.4 keV transition to the ground state. A new gamma transition of energy 202.5 ± 0.1 keV was found, decays from the 279 keV excited level in 197Au, with an E2 character. The internal K-conversion coefficients of most transitions in 197Pt and 197Au were determined by the internal-external conversion method. The K-internal conversion coefficient of the 191 keV transition in 197Au indicated no E0 contribution. Multipolarity data, obtained from the absolute or ratios measurements of conversion coefficients, were utilized for assigning possible spins and parities to the levels in 197Pt and 197Au.