Ultraviolet Through Mid-Infrared Optical Constants of Minerals and Glasses Relevant to Planetary Spectroscopic Analyses

THE GOAL OF OUR PROPOSED WORK IS TO DETERMINE THE COMPLEX REFRACTIVE INDICES (OPTICAL CONSTANTS) OF A RANGE OF MINERALS AND GLASSES OVER THE 0.35-50 M WAVELENGTH RANGE. OUR WORK WILL RESULT IN ROBUST OPTICAL CONSTANTS FOR MAJOR ROCK FORMING MINERALS INCLUDING FELDSPARS AND PYROXENES ALTERATION PHASES INCLUDING SULFATES AND CARBONATES AND SIX SYNTHETIC GLASSES RANGING IN COMPOSITION FROM ULTRAMAFIC TO FELSIC AND LOW TO MODERATE ALKALI CONTENTS. THIS WORK WILL UTILIZE MODELS PREVIOUSLY DEVELOPED BY THE PI S RESEARCH GROUP UNDER PREVIOUS FUNDING FROM BOTH NASA AND NSF. MID-IR (~2.5-50 MICRONS) OPTICAL CONSTANTS WILL BE DETERMINED USING VARIATIONS OF LORENTZ-LORENZ DISPERSION THEORY OPTIMIZED FOR THE CRYSTAL SYMMETRY OF EACH PARTICULAR MINERAL OR GLASS SAMPLE. OUR PREVIOUS WORK HAS RESULTED IN MODELS AND METHODS APPLICABLE TO THE MONOCLINIC AND TRICLINIC CRYSTAL SYSTEMS. POLARIZED SPECTRA OF ORIENTED SINGLE CRYSTALS WILL BE ACQUIRED AT THE APPROPRIATE NUMBER OF ORIENTATIONS AND SIMULTANEOUSLY MINIMIZED TO SOLVE FOR ONE (ISOTROPIC MATERIALS SUCH AS GLASS) TWO (HEXAGONAL MINERALS) OR THREE (ORTHORHOMBIC AND LOWER SYMMETRY MINERALS) PRINCIPAL INDICES OF REFRACTION. VISIBLE/NEAR-INFRARED BULK OPTICAL CONSTANTS WILL BE DETERMINED FOR THE SAME MINERAL AND GLASS SAMPLES USING A ROBUST HAPKE SCATTERING MODEL THAT DETERMINES THE IMAGINARY REFRACTIVE INDEX (K) BY MINIMIZING THE MODEL ON 21 SEPARATE SPECTRA (THREE GRAIN SIZE FRACTIONS ACQUIRED AT SEVEN PHASE ANGLES EACH) BEFORE ITERATIVELY DERIVING THE WAVELENGTH-DEPENDENT REAL REFRACTIVE INDEX (N) AND AN OPTIMIZED K USING AN ITERATIVE KRAMERS-KRONIG APPROACH. THE PRIMARY SAMPLE PREPARATION SPECTRAL ACQUISITION AND MODELING TASKS WILL BE CONDUCTED BY POSTDOCTORAL RESEARCHER ELIZABETH SKLUTE (0.5 FTE) AND A 1.0 FTE GRADUATE STUDENT AT STONY BROOK UNIVERSITY SUPERVISED BY THE PI. THE PI WILL BE RESPONSIBLE FOR ORGANIZING ALL DATA IN A FORMAT APPROPRIATE FOR THE PDS AND SUBMITTING THE DATA TO THE PDS IN A TIMELY MANNER. IN ADDITION FULLY DOCUMENTED AND COMMENTED CODES WILL BE MADE AVAILABLE AND SUBMITTED TO NASA S PSD GITHUB SITE.