MASS-SPECTROMETRIC IDENTIFICATION OF SI-O-H(G) SPECIES FROM THE REACTION OF SILICA WITH WATER-VAPOR AT ATMOSPHERIC-PRESSURE

A high-pressure sampling mass spectrometer was used to detect the vola tile species formed from SiO2 at temperatures between 1200 degrees and 1400 degrees C in a flowing water vapor/oxygen gas mixture at 1 bar t otal pressure. The primary vapor species identified was Si(OH)(4). The fragment ion Si(OH)(3)(+) was observed in quantities 3 to 5 times lar ger than the parent ion Si(OH)(4)(+). The Si(OH)(3)(+) intensity was f ound to have a small temperature dependence and to increase with the w ater vapor partial pressure as expected. In addition, SiO(OH)+, believ ed to be a fragment of SiO(OH)(2), was observed. These mass spectral r esults were compared to the behavior of silicon halides.