Fluorescence of SiO Condensate in Near Infrared Region

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In reflection nebulae, extended red excess emission(ERE)are observed. The emission is come from the dust irradiated with emission of a central star. Authors proposed the emission can be caused by the carbonaceous dust alike quenched carvonaceous composite(QCC, ApJ1992). A dust, which has Si-O network structure, may exit in reflection nebulae. In this work, we measured fluorescence spectra of SiO condensates and discussed contribution of the SiO fluorescence to the ERE.We made three kinds of SiO condensate materials ; (1) SiO condensate which was made as a deposit from SiO gas, (2) oxidize SiO condensate which was made with an exposure of the SiO condensate to air, (3) thermally altered SiO condensate which was made with heating of the SiO condensate to 650 C in vacuum.We measured fluorescence spectra of the SiO condensate materials with two spectroscopy systems ; in one system, Ar laser (488.4 nm, 2mW)is used for excitation and two kinds of dectors, Si detector (500-1000 nm)and Ge detector(750-1500 nm), are used for detection and in the other system, Hg-Xe lamp (313nm)is used for excitation and two kinds of dectors, photo-multiplier (R666 and R376, 400-800 nm)and Ge detector (750-1500 nm), are used for detection.In both fluorescence measurements of untreated SiO condensate and thermally altered SiO condensate, we did not detect obvious emission. In the measurement of oxidized SiO condensate weak yellow emission with a peak wavelength at 480-550 nm was detected with using the photo-multipliers.According to our measurement, the "SiO condensate dust" cannot be a candidate of the ERE emitter in the reflection nebulae.