Analysis of carbonaceous materials which show "217.5<plus-minus>2.5 nm hum

星际消光曲线是银河系中星际尘埃的光谱。在光谱中，我们可以看到一个清晰的217.5 nm的驼峰和一个非常宽的500 nm的驼峰。QCC（淬火碳复合材料）是一种由碳氢化合物等离子体形成的无定形碳质材料。在Sakata等1994年的论文中，我们研究了两种形式的QCC：位于等离子体束附近的暗QCC分量和热变薄膜QCC，这两种类型的QCC衍生物在217 nm附近都显示出吸收特征，但消光幅度不同。我们发现，从甲烷，甲烷-氢气的混合气体产生的煤烟，有一个广泛的消光功能中心约217 nm。在这项工作中，我们提出了一种新的材料，中间相沥青，它具有217 nm的消光功能。中间相沥青是由Asahi Coke Ltd.的原料沥青经加热至-450 ℃制得的，其化学分析表明H/C= 0.52。这三种物质均在富氢环境下形成，峰高约217 nm。从中间相沥青的化学组成可以推断，具有217 nm特征的碳质材料在其结构中含有大量的氢。

Interstellar extinction curve is a spectrum of interstellar dust in our Galaxy. In the spectrum we can see a clear 217.5 nm hump and and very broad-500 nm hump.QCC (Quenched Carbonaceous Composite) is an amorphous carbonaceous material formed from a hydrocarbon plasma. In a previous paper (Sakata et al.1994), we have studied two forms of QCC : a dark QCC component located near the plasmic beam and a thermally-altered filmy QCC.Both types of QCC derivatives show an absorption feature near 217 nm but with different extinction magnitude. And we showed that soots produced from methane, methane-hydrogen gas mixtures, have a broad extinction feature centered at about 217 nm.In this work we present a new material, mesophase pitch, which has a 217 nm extinction feature. The mesophase pitch was produced from raw pitch by heating to -450 C,by Asahi Coke Ltd. Chemical analysis of the mesophase pithc showed H/C=0.52.These three kinds of materials showing about 217 nm hump were formed under hydrogen rich environment. From the chemical composition of mesophase pitch, we can deduce that the carbonaceous materials having 217 nm feature contain a large amount of hydrogen in their structure.