Burchard, M.

Glasmacher, U. A.

Schöppner, N.

Trautmann, C.

GSI Repository

GSITemplate2007 Raman measurements of heavy ion irradiated water-bearing  minerals*	Nicole Schöppner1#, Ulrich A. Glasmacher1, Michael Burchard1, Christina Trautmann2 1Institute of Earth Sciences, University of Heidelberg, Heidelberg, Germany; 2 Technische Universität Darmstadt and GSI Helmholtzzentrum Darmstadt, Germany  Our research was triggered by the question if crystal water of natural minerals is released during irradiation with swift heavy ions. To answer this question natural microcrystalline malachite (Cu2[(OH)2/CO3]) and gypsum (CaSO4*2H2O) were irradiated at the UNILAC (GSI) with 11.1 MeV/u 209Bi-ions applying fluences between 1×106 – 2×1012 ions/cm2. All crystals were analyzed by Raman spectroscopy using the LabRam HR800 UV spec-trometer equipped with an OLYMPUS BXFM-ILHS op-tical microscope, a grating with 1800 grooves per milli-meter, a Peltier-cooled CCD detector, and an objective of 50x magnification. For excitation, a blue laser with a wavelength of 473.03 nm was used. The lateral resolution was ~2 µm, the wave number accuracy 0.5 cm-1, and the spectral resolution 1 cm-1.  Malachite and gypsum are both anisotropic crystals, have a monoclinic structure and two optical axes. Mala-chite has variable crystallographic orientations and growth directions and consequently the intensities of the different malachite bands vary. This variation is demon-strated in Fig. 1 for spectra recorded under different crys-tallographic directions and cleaving planes. For irradiated gypsum, significant changes in the Raman spectra appear above a fluence of 1×1010 Bi-ions/cm². With increasing fluences the intensity of most Raman bands decreases. This applies especially to the       Fig. 1: Raman spectra of gypsum (top) and malachite (bottom) at different crystal orientations.   ʋ1 stretching mode at 3404 cm-1 and the ʋ3 stretching mode at 3492 cm-1, which characterize the H2O bands. The decrease of amplitudes is an indication of irradiation-induced release of water. Although the lattice water is set free, the mineral is not transformed to anhydrite (CaSO4), which is the waterless sulfate. The bands remain at their characteristic gypsum position and do not shift to the an-hydrite position.  Also for malachite the amplitude of different Raman bands decrease with increasing fluence. In contrast to the Raman bands of gypsum, the OH stretching vibration modes at 3308 and 3380 cm-1 of malachite are equal sen-sitive than the other bands. Significant changes in the spectra as well as discoloration of the crystal (Fig. 2) also appear above a fluence of 1×1010 Bi-ions/cm². The color change from green to black indicates a phase transfor-mation of the irradiated layer showing Raman bands at ~1360 cm-1 and ~1580 cm-1, typical for graphite. Under irradiation, the band positions in the malachite spectra slightly change but not systematically.   Fig. 2: Malachite sample showing the beginning of discoloration at a fluence of 1×1010 Bi-ions/cm² at the right site of the red line. The left side of the crystal is non-irradiated for comparison.  References [1] S. Dedera, U. A. Glasmacher, M. Burchard , C. Trautmann. "Annealing of Dislocations and Heavy-Ion Induced Tracks in Calcite." In Scientific Report 2011, 2012-1, 689. Darmstadt: GSI, 2012.  [2] S. Dedera, U. A. Glasmacher, M. Burchard and C. Trautmann. "Optimized Etching of Swift Heavy Ion Tracks in Calcite." In Scientific Report 2012, 2013-1, 400 p. Darmstadt: GSI, 2013. ---------------------------------- *Work supported by HGS-HIRe #nicole.schoeppner@geow.uni-heidelberg.de APPA-MML-MR-12 GSI SCIENTIFIC REPORT 2014264 DOI:10.15120/GR-2015-1-APPA-MML-MR-12

Raman measurements of heavy ion irradiated water-bearing  minerals

http://repository.gsi.de/record/183998/files/APPA-MML-MR-12.pdf

Raman measurements of heavy ion irradiated water-bearing minerals

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