Structure of interstellar carbonaceous dusts and their surface.

淬火碳质复合材料（QCC）是一种由碳氢化合物等离子体喷出物凝聚而成的碳质材料。A.Sakata和他的同事已经证明QCC具有220 nm的吸收特征，一组红外吸收带对应于反射星云，HIT区域和行星状星云中的红外发射特征，并且显示出与反射星云中看到的延伸红色发射相匹配的可见荧光。这些特性使Q CC成为星际介质中碳质物质的实验室模拟物的有力候选材料。高分辨率透射电子显微镜（HRTEM）显示，暗qcc是碳质洋葱样颗粒的混凝物。每个粒子由多个壳层组成，许多粒子的中心有一个空洞。HRTEM图像表明，颗粒在结构上有许多缺陷位点。通过将QCC暴露于氢气中，深色QCC粒子中的缺陷位点容易与氢分子发生反应。结果表明，在3.42、3.51、6.9、7.3、12.5 nm处的红外吸收峰强度有所增加，但dark-QCC在220 nm处的吸收峰保持稳定。另一方面，在222nm紫外线照射和黑暗条件下，薄膜- qcc均不与氢发生反应。为了进一步阐明分子云化学，我们需要对候选材料的表面进行更多的研究。

Quenched Carbonaceous Composite (QCC) is a carbonaceous material condensed from an ejecta of hydrocarbon plasma. A.Sakata and his colleagues have shown that QCC has a 220 nm absorption feature, a set of infrared absorption bands that correspond to the infrared emission features in reflection nebulae, HIT regions, and planetary nebulae, and exhibits visible fluorescence matching the extended red emission seen in reflection nebulae. These properties make Q CC a strong candidate material as a laboratory analog to the carbonaceous material in the interstellar medium.High-resolution transmission electron micrographs (HRTEM) revealed that the dark-QCC is a coagulation of carbonaceous onion-like particles. Each particle consists of multiple shells, and many of the particles have a void at the center. The HRTEM images implied that the particles have many defected sites in their structure.By exposuring of the QCC with hydrogen gas, the defected sites in the dark-QCC particles were reacted with hydrogen molecules easily. As a result, peak intensities of infrared absorption bands at 3.42, 3.51, 6.9, 7.3, 12.5mum were increased, However, the 220 nm absorbance peak of the dark-QCC was stable. On the other hands, the filmy-QCC did not react with hydrogen both under irradiation of uv (222nm) and under dark condition.In order to clarify molecular cloud chemistry, we need more studies about the surface of the candidate materials.