Comment on ‘Modification of vacuum-ultraviolet absorption of SiOH groups in SiO2 glass with temperature, F2 laser irradiation, and H–D isotope exchange’ by K. Kajihara et al. [J. Non-Cryst. Solids 2307 (2006)]

The modification of SiOH groups in SiO2 by F2 laser irradiation studied in the paper by Kajihara et al. [K. Kajihara, M. Hirano, L. Skuja, H. Hosono, J. Non-Cryst Solids 352 (2006) 2307] is discussed on the base of ab initio calculations. The calculated energy barrier of transformation of an oxygen tricluster (bridging oxygen forming the third covalent bond with an hydrogen atom) into a silanol group and the frequency of OH stretching vibration in the tricluster suggest that the triclusters can be products of F2 laser irradiation of ‘wet’ silica glass.