Optical properties of candidate minerals for circumstellar dust in the UV - Far infrared region and application for Infrared Astronomy

对于不同的星际尘埃候选物质，我们研究了温度对微粒子红外光谱的影响。尤其是温度对橄榄石颗粒光谱的影响，从室温降温到10K左右，各峰的强度变强，半峰宽变窄，各峰的位置向较短的波长移动。这些趋势在中红外区较为平缓，而在远红外区则非常明显。特别是对于镁橄榄岩，49和69μm的位置和半宽度成为温度指示器。我们合成了镁橄榄岩端元附近的橄榄石样品，发现49和69μm峰随着Fe含量的不同发生了很大变化。在此基础上合成了含钙、钠、铝等元素的硅酸盐晶体，…进一步明确了峰位置与成分之间的关系。采用Sol-Gel法合成了含球粒石组分的无定形硅酸盐，研究了晶化过程，研究了晶化过程中红外光谱的变化；对于镁橄榄石大块样品，从测得的中、远红外反射率可以得到令人满意的各轴光学常数。在此基础上，将镁橄榄石样品连续冷却至10K左右，测量了样品在中、远红外区的3个轴的反射率。然后，我们从许多低温下的反射率得到了每个轴的光学常数。对于69μm波段的反射率，10K时的强度是室温时的3倍。另一个远红外峰也显示出类似的趋势。我们清楚地表明，每个轴的光学常数取决于温度。根据光学常数，任何人都可以计算出不同形状的光谱，如针状、扁圆形、比例状和苍白状。以镁橄榄岩的椭圆形和茎花为例，在实验室内确定了形状效应。较少

For various candidates materials for circumstellar dusts, we investigated the temperature effects on infrared spectra of fine particles. Especially, as for temperature effects on spectra of olivine particles cooling down from room temperature to about 10 K, the intensity and half width of each peak became strong and narrow, respectively, and the position of each peak shifted to shorter wavelength. These tendencies were gentle in mid infrared region, but were very distinct in far infrared region. In particularly for the case of forsterite, the position and half width of 49 and 69μm were shown to be become the temperature indicator. That is, any observer can know the dust temperature from the observed position and half width in circumstellar or interstellar region.We synthesized olivine samples near end member of forsterite and made clear that the 49 and 69μm peak changed drastically according to the Fe content. Further we synthesized silicate crystalline including Ca, Na, Al elements, a … More nd the correlation between peak position and composition was made clear. Amorphous silicates with chondritic components were synthesized by Sol-Gel method, and the process to crystallization was made clear studying the change of infrared spectra after annealing.As for bulk sample of forsterite, we can obtained the satisfactory optical constants for each axis from each measured reflectance in mid and far infrared. Further, cooling the bulk sample of forsterite continuously to about 10 K, the reflectance were measured in mid and far infrared region for 3 axis. Then, we obtained the optical constants for each axis from the reflectance at many low temperature. As for the reflectance of 69μm band, the intensity become 3 times at 10 K compared to at room temperature. Another peaks at far-infrared also showed similar tendencies. We made clear the optical constants for each axis depend on temperature. From the optical constants, anyone can calculate the spectra in various shape such as needle, oblate, prorate and pale. The shape effects were ascertained in laboratory in the case of ellipse and cauli flower of forsterite. Less