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 Sen+ ions between n = 1 and n = 8 were detected in measurable quantities. The ions Se5+, Se6+, Se7+, and Se8+ arise mainly from ionization of the corresponding parent molecules, which are believed to be cyclic. At 175 °C the composition of the vapor is Se5 ≤ 29.0%, Se6 ≥ 57.5%, Se7 ≥ 11.4%, and Se8 ≥ 2.0%. Thermodynamic data are reported for the sublimation of these molecules. Small amounts of Se9+ and Se10+ were also detected.