MASS SPECTROMETRIC STUDY OF SUBLIMING SELENIUM

In the mass spectrum of the vapor from grey selenium subliming in the temperature range 102 to 187 °C all possible Se n + ions between n = 1 and n = 8 were detected in measurable quantities. The ions Se 5 + , Se 6 + , Se 7 + , and Se 8 + arise mainly from ionization of the corresponding parent molecules, which are believed to be cyclic. At 175 °C the composition of the vapor is Se 5 ≤ 29.0%, Se 6 ≥ 57.5%, Se 7 ≥ 11.4%, and Se 8 ≥ 2.0%. Thermodynamic data are reported for the sublimation of these molecules. Small amounts of Se 9 + and Se 10 + were also detected.