Spectroscopic Studies of Ruby during Shock Loading.
Abstract
Experimental techniques have been developed to obtain time resolved emission data at 77 K and polarized absorption data during shock loading. Single crystal ruby discs, encapsulated between z-cut sapphire discs, were shocked along the crystal c-axis to longitudinal stresses up to 120 kbar (below the yield limit of ruby). In the low temperature emission experiments, the ruby R lines were examined during loading and unloading. Both lines shift to lower energies and the splitting decreases with increasing compressive strain. These results are in good agreement with room temperature data corrected for temperature changes. The mean shift of the R lines as a function of density compression is within 2 percent of the hydrostatic shift. The changes in the R lines splitting, not observed during hydrostatic compression, are a consequence of nonhydrostatic deformation and reflect changes in the low symmetry crystal fields around the Cr^{3+} ion. Despite the nonhydrostatic state of stress, no line broadening is observed in contrast to the hydrostatic data. The ^4E components of the Y and U bands were examined in the polarized absorption experiments. With light polarized perpendicular to the crystal c-axis, both bands shift to higher energies with increasing compressive strain. The results for the Y band are difficult to interpret quantitatively due to experimental problems encountered during the early part of the absorption work. More precise results for the shift of the U band with density compression agree closely with the hydrostatic data. This similarity in energy shifts between the shock and hydrostatic data implies that changes in the octahedral field strength are only weakly sensitive to the nature of the applied stress. A more complete understanding of changes in the lower symmetry crystal fields during shock loading would require absorption measurements with polarization parallel to the c-axis. The experimental developments presented here are expected to be helpful in relating the effects of stress to changes in the optical properties of impurity doped crystals.
- Publication:
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Ph.D. Thesis
- Pub Date:
- 1989
- Bibcode:
- 1989PhDT.......185B
- Keywords:
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- Physics: Condensed Matter; Chemistry: Physical