抄録
A mass spectrometric method for measuring the isotope ratio of sulfur was required for the purpose of evaluating the results of experiments on sulfur hexafluoride in a project related to centrifugal separation. The present report covers results obtained in determining the various conditions governing the mass spectrometry of sulfur hexafluoride. The SF+5 ion was adopted for the sulfur isotope ratio measurements. The ratio was determined from the pattern coefficient of the fragment ions produced upon ionization of sulfur hexafluoride by electron impact. An ATLAS CH4 type mass spectrometer made in Germany was used.
Further experiments were undertaken to determine the most favorable conditions for measuring the 34S/32S isotope ratio in respect of specimen gas pressure, volume of electron beam and electron energy.
The optimum conditions thus determined were; Specimen gas pressure: 2.88×10102mmHg, Electron beam: 70-80μA, Electron energy: 30-40eV.
As an example of the accuracy attainable under the best conditions, a 34S/32S value of 4, 200±0.008 was obtained.
