Destructive Processing of Silicon Carbide Grains: Experimental Insights into the Formation of Interstellar Fullerenes and Carbon Nanotubes
Destructive Processing of Silicon Carbide Grains: Experimental Insights into the Formation of Interstellar Fullerenes and Carbon Nanotubes
复制标题
碳化硅颗粒的破坏性加工：星际富勒烯和碳纳米管形成的实验见解
DOI：
10.1021/acs.jpca.2c01441
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Ziurys, Lucy M.
中科院分区：
文献类型：
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作者：
Bernal, Jacob J.;Zega, Thomas J.;Ziurys, Lucy M.
星际介质（ISM）中富勒烯c60和c70的探测改变了我们对太空化学复杂性的理解。这些发现也提高了在天体物理环境中存在更大分子的可能性。本文报道了利用透射电子显微镜（TEM）原位加热模拟碳化硅（SiC）太阳前颗粒。这些加热实验旨在模拟发生在agb后恒星包层的温度条件。实验结果表明，将模拟碳化硅晶粒加热到分解点，最初会产生具有五元和六元环的半球形碳纳米管结构，如果等温保持bbbb2分钟，它们会转变为多壁碳纳米管（MWCNTs）。这些MWCNTs肯定比目前观察到的任何星际富勒烯种类都要大，无论是总体尺寸还是C原子数量。这些实验模拟表明，这种MWCNTs很可能在agb后的星周材料中形成，其中结构以及较小的富勒烯随后被注入ISM。
The detection of the fullerenes C60and C70in the interstellar medium (ISM) has transformed our understanding of chemical complexity in space. These discoveries also raise the possibility for the presence of even larger molecules in astrophysical environments. Here we report in situ heating of analog silicon carbide (SiC) presolar grains using transmission electron microscopy (TEM). These heating experiments are designed to simulate the temperature conditions occurring in post-AGB stellar envelopes. Our experimental findings reveal that heating the analog SiC grains to the point of decomposition initially yields hemispherical C60-sized nanostructures, with five- and six-membered rings, which transform into multiwalled carbon nanotubes (MWCNTs) if held isothermally >2 min. These MWCNTs are certainly larger than any of the currently observed interstellar fullerene species, both in overall size and number of C atoms. These experimental simulations suggest that such MWCNTs are likely to form in post-AGB circumstellar material, where the structures, along with the smaller fullerenes, are subsequently injected into the ISM.