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

针对不同的星周尘埃候选物质，研究了温度对细粒子红外光谱的影响。特别是当温度从室温降到10 K左右时，橄榄石粒子的光谱随温度的变化，各峰的强度变强，半峰宽变窄，峰位向短波长方向移动。这些变化在中红外区比较平缓，而在远红外区则非常明显。特别是对于镁橄榄石，49和69μm的位置和半宽被证明是温度指示器。我们在镁橄榄石的端员附近合成了橄榄石样品，发现49和69μm峰随Fe含量的变化而发生剧烈的变化。在此基础上合成了含有Ca、Na、Al元素的硅酸盐晶体， 关于我们 明确了峰位与组成的相关性。采用溶胶-凝胶法合成了镁橄榄石型无定形硅酸盐晶体，通过研究退火后红外光谱的变化，明确了镁橄榄石的晶化过程，并对镁橄榄石块体样品进行了中、远红外反射率的测定，得到了满意的各轴光学常数。将镁橄榄石块体样品连续冷却至10 K左右，在中远红外区测量了3个轴向的反射率。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，在10 K时的强度是室温时的3倍。在远红外处的另一个峰也显示出类似的趋势。我们明确了每个轴的光学常数取决于温度。从光学常数出发，任何人都可以计算出各种形状的光谱，如针状、扁圆状、比例状和苍白状。在实验室条件下，以镁橄榄石的椭圆形和茎花形为例，确定了形状效应。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