Abstract
The 2-modulator generalized ellipsometry microscope (2-MGEM) has been used to study a natural crystal of aragonite. Like its polymorph calcite, aragonite has a large refractive index difference between light polarized parallel to the c-axis and light polarized perpendicular to the c-axis. Unlike calcite, aragonite is orthorhombic, so there is also a very small difference between the refractive indices polarized along the a- and b-directions. As a result, it is not possible to use the 2-MGEM to obtain a definitive map of the optic axis directions of a sample as was possible with calcite, but it is possible to determine approximately the orientation of the c-axis with respect to the surface normal. If the c-axis is in the sample surface plane, it is possible to measure very small deviations of the c-axis direction with an accuracy of ∼0.2°. If the c-axis is oriented normal to the sample surface, 2-MGEM data can be used to identify different crystallites due to rotations about the c-axis. For comparison, the orientations of some of the crystallites have also been measured using X-ray Laue and electron beam backscatter diffraction. In addition, spectroscopic generalized ellipsometry measurements have been used to determine the refractive indices of aragonite.
Original language | English |
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Article number | 043102 |
Journal | Journal of Applied Physics |
Volume | 126 |
Issue number | 4 |
DOIs | |
State | Published - Jul 28 2019 |
Bibliographical note
Publisher Copyright:© 2019 Author(s).