Platinum Isotopes and their Nuclear Spin

Abstract

Using a water-cooled hollow cathode of a new design, the hyperfine structure of the are lines of platinum 3408 and 3042 A. have been studied. These two lines have a common lower level 5d⁸6s²a³F₄ ; and the similarity of their structure patterns leads to the conclusion that in neither case is the upper level split. The lines have the following structure: An examination of the structure leads to the unique inference that the three central components 0.000 (18), — 0.086 (7) and — 0.176 (1) have to be ascribed to the even isotopes 196, 194 and 192 respectively, the remaining two components being due to the odd isotope 195 with a nuclear spin of ½h/2. The centre of gravity of the latter components falls at — 0.050 cm.¹ between the bright components due to 196 and 194. The deeper level 5d⁹6sa³D₂ shows no measurable isotopic displacement. The hyperfine levels in platinum are inverted. These results are confirmed by the analysis of eight other arc lines of platinum, namely, 2998, 2929, 2734, 2719, 2705, 2702, 2659 and 2650 A. Neglecting isotopes of small abundance, the isotopes of platinum, purely from hyperfine structure data, in decreasing order of their relative abundance, are 196 (18), 195 (9), 194 (7) and 192 (1). The relative isotopic abundance given above is from eye-estimates of the intensities of the components and is to be checked by microphotometric measurements.