Modulated-beam mass spectrometry has been used to investigate the ion-induced etching of SiO2 in the presence of a flux of XeF 2. The types of desorbed etch product are characterized. It is also demonstrated directly that mixing leads to an enhanced etch rate while the presence of lattice damage does not produce spontaneous etching. It is concluded that all available data for the etching of SiO2 with XeF2 is consistent with the original hypothesis of Y. Y. Tu, T. J. Chuang, and H. F. Winters [Phys. Rev. B 23, 823 (1981)], that the etching reaction is primarily based on a mechanism involving chemical sputtering.