Development of Near Infrared Microspectroscopy and its Application to Spectroscopic Study on Opaque Minerals.

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1. We developed a spectroscopic equipment which enables us to obtain in-situ near infrared (NIR) spectra from a small region of praque minerals imaged with an NIR optical microscope. NIR output light was intyroduced to an emission port of FTIR spectrometer (Perkin Elmer Spectrum 2000) using aluminum mirrors. The present system can show the availability of this optical arrangement, but further improvement will intensively increase in the sensitivity.2. Relationship between molybdenite alteration, and its NIR spectrum and Re-Os age was investigated. Molybdenite was altered at 180 ﾟC for 20 days in various solutions, such as CaCl_2, AlCl_3, NaCl, NaHCO_3 and H_2O.In the latter three cases, little changes could be found in NIR transparency. IN molybdenites altered in CaCl_2 and AlCl_3, on the contrary, increase in transparency of NIR in some parts of molybdenites was observed. In these two cases, it was also found that the absorption edges observed in ca. 3250 cm^<-1> were moved to the boundary region between visible and IR, which indicates increase in band gap of molybdenite. Incidentally, it was found that fractionation in Re-Os system is not necessarily associated with its NIR transparency.3. The OH stretching + HOH bending combination mode of molecular water was found to be a promising indication for the chemical state of molecular water in natural samples. In natural samples, it is fairly difficult to distinguish between OH ion and molecular water only from OH stretching band. The combination band observed in NIR region is exclusively from molecular water. We observed the combination band of water in cubic diamonds, and the temperature dependence of band shape demonstrated the presence of high pressure phase of ice in one of the samples.