Reply to the comment by E. Libowitzky on ''Behaviour of H2 O and OH in lawsonite: a single-crystal neutron diffraction and Raman spectroscopic investigation''

Abstract

The interpretation of the Raman spectra of lawsonite at various temperatures proposed in our article (Kolesov et al. , 2008) was based first of all on structural data. The numerous crystal-structure studies (Libowitzky & Armbruster, 1995; Libowitzky & Rossman, 1996; Meyer et al. , 2001; Kolesov et al. , 2008) show that the space group of lawsonite at T ≥ 270 K is Cmcm . A set of symmetry operations of the group involves a mirror plane perpendicular to the water molecule plane in the crystal that fixes the symmetrical state of H2O and its arrangement. Considering the single-crystal polarized Raman spectra of lawsonite, we found a few spectral features that also indicate a symmetrical state of the H2O molecule at ambient temperature. All these features were described in detail in our paper. However, the vibrational (Raman and IR) spectra of the water molecule and hydroxyl groups in lawsonite at room temperature are really complicated and consist of several broad and overlapping bands. For this reason the presented assignment of the Raman spectra resulted in the publication of the “Comment” and we try here to resolve the questions raised.