Study on mutual interaction between high energy ion beams and carbon materials related to interstellar material

本研究是利用筑波大学串列加速器中心（UTTAC）的束线上安装的新设计的“温度可调样品辐照室”进行的。对于辐照样品，首先采用简单的碳材料，如石墨，煤，合成和天然金刚石，而不是星际尘埃状碳材料，如PAH，因为它们的结构简单。用不同能量和电流的质子束辐照阶梯状样品保持器上的样品。在实验过程中，在金刚石样品上观察到发光。由于离子发光现象的报道很少，而发光是探测晶体中结构缺陷形成和变化的一种非常灵敏的探针，因此我们研究了质子束轰击金刚石引起的离子发光现象。离子发光光谱是在液氮附近拍摄的。 ...更多信息 EN温度，并与阴极发光光谱进行了比较。在辐照开始时，光谱与阴极发光的光谱几乎相似，但在辐照后期观察到几个新的峰。PIXE和离子发光的结合分析将是分析缺陷中杂质的种类和结构的有效方法，采用FTIR、拉曼光谱、ESCA等光学方法对辐照后的样品进行了研究，结果表明，虽然观察到石墨结构向无定形碳的分解和无定形碳向石墨的转变生长，在该研究中没有检测到从其它相到金刚石结构的转变。然而，所有陨石中的金刚石和高铀含量的煤中发现的金刚石，这可能与宇宙射线的照射或铀的辐射有关，都是埃尺寸的，可以想象，这种转变只能稳定在埃尺寸。如果金刚石是埃尺寸，本研究中使用的光学方法无法检测到如此小尺寸的相。我们现在正在进行的石墨和非晶相的辐照碳样品使用过氧化氯浓缩可能的金刚石相的辐照实验中出现的抽空实验。利用透射电镜和扫描电镜对真空试验后的残留物进行了观察。我们将继续这项研究，并将样品扩展到其他碳材料，如PAH。少

This study was carried out using a newly designed "Temperature adjustable specimen irradiation chamber" installed on a beam line in the UTTAC (University of Tsukuba Tandem Accelerator Center). For the irradiation specimen, simple carbon materials such as graphite, coal, and synthetic and natural diamonds were firstly employed instead of interstellar dust like carbon materials such as PAH because of their simple structures. The specimens on a ladder like specimen holder were irradiated by proton beams of different energies and currents. During the experiments, luminescence was observed on the diamond specimens. We investigated this ion-luminescence of diamond caused by the proton beam bombardment as the part of this study, because there are very few reports on the ion-luminescence phenomena, and the luminescence is a very sensitive probe on the detection of the formation and alteration of the structural defect in crystal. The ion-luminescence spectra were taken at near the liquid nitrog … More en temperature and were compared with those of cathode luminescence spectra. The spectra were almost similar to those of cathode luminescence at the beginning, but several new peaks were observed at the late stage of the irradiation. The combination analysis of PIXE and the ion-luminescence will be an effective method for analyzing the species and the structures of impurities in the defect.The irradiated specimens were investigated by the optical methods such as FTIR,Raman spectrometry, ESCA,etc. As the results, although the break down of graphite structure to amorphous carbon, and the alteration growth from amorphous to graphite were observed, transformation to the diamond structure from other phases was not detected in this investigation. However, all the diamonds in meteorites and the diamond found in coal with high U content, which may be related with irradiation of cosmic-ray or radiation of U,are in Angstrom size, and it is conceivable that this transformation can be stabilized only in the Angstrom size. If diamond is Angstrom size, optical methods used in this study are not able to detect such a small size phases. We are now carrying out evacuation experiment of the graphite and amorphous phases in the irradiated carbon specimens using chlorine peroxide for concentrating the possible diamond phase occurred by the irradiation experiments. The residues of this evacuation experiments are observed by TEM and SEM.This observation is now on the way. We will continue this study and extend the specimen to other carbon materials such as PAH. Less