Similarities between the processes that occur during sputtering of monocrystalline Si by reactive O2+primary ions and the interface SiO2/monocrystalline Si by noble gas ions (e.g., by Ar+) have motivated us to utilize the semiempirical model of P. C. Zalm and C. J. Vriezema [Nucl. Instrum. Methods B67, 495 (1992)], modified later by M. Petravic´, B. G. Svensson, and J. S. Williams [Appl. Phys. Lett.62, 278 (1993)] to calculate the decay length &lgr;b, as defined by J. B. Clegg [Surf. Interface Anal.10, 322 (1987)], at the SiO2/Si interface. The measured and calculated results agree remarkably well. Inconsistency observed to be larger than 100% for glancing incidence angles confirms limitations of this model that were admitted already by its authors. ©1995 American Institute of Physics.