Nanotextures of aragonite in stromatolites from the quasi-marine Satonda crater lake, Indonesia - Tufas and Speleothems: Unravelling the Microbial and Physical Controls - page 216

Fig. 6. STXM mapping of the orientation of the c-axis of aragonite in the FIB foil. (a) XANES spectra at the C K-edge
of a single aragonite crystal measured at two perpendicular orientations of the beam polarization, either parallel or
perpendicular to the c-axis of aragonite. The dashed line indicates the absorption peak at 290.3 eV attributed to
1s ! p* electronic transitions of carbonate groups. Absorption at this energy is higher when the polarization vector of
the beam is parallel to the c-axis of aragonite, and lower when perpendicular. (b-g) STXM images taken at 290.3 eV
of the FIB foil with varying directions of the polarization of the incident X-ray beam (0, 20, 40, 60, 70 and 908),