Direct observation of molecular structure by Coulomb explosion imaging

为了建立库仑爆炸成像技术（CE 1），进行了高电荷态离子与不同分子的碰撞实验。利用ECR离子源产生的Ar高离化束碰撞多电荷分子离子，诱导其解离，并根据碎片的位置和飞行时间计算出碎片的运动轨迹。主要研究结果如下：1：通过检测线性三原子分子CO_2和CS_2以及非线性三原子分子NO_2的所有碎片，实现了CEI。结果与已知的键角一致。通过电荷的变化和碰撞能的变化，详细分析了解离碎片的速度矢量。通过对CD_4分子的C-D-D三重符合测量（部分碎片的检测）的GEI实验，证明了D-C-D键角的准确性。这一结果表明了用CEI方法进行局域结构分析的可能性。3：分析了零点振动畸变的CD_4分子的手性，证明了CEI方法可以直接区分分子的手性。4：研制了电阻衬底与步步高型电极相结合的新型位置灵敏检测器。结果表明，该系统获得了很高的位置和时间分辨率，并在国内外学术会议上发表了论文。并且，为了从新的观点分析富勒烯的解离过程，制造了用于富勒烯与高电荷离子的碰撞实验的测试设备，并进行了产物的初步飞行时间分析实验。

To establish the technique "Coulomb explosion imaging (CE1)", collision experiments of highly charged ions with various molecules were carried out. Dissociation of the multiply charged molecular ion was induced by the collision of Ar highly ionized beam extracted from an ECR ion source, and the trajectories of the fragments were derived from the values of the positions and the time-of-flights. The main results are as follows.1 : CEI was done by the detection of all fragments of linear triatomic molecules, CO_2 and CS_2, and nonlinear triatomic molecule, NO_2. The results were consistent with the known bond angles. The velocity vectors of the dissociating fragments were analyzed in detail by the change of charge and the collision energy. It was clarified that the charge states of the target molecule are the most critical factor governing dissociation process.2 : By GEI based oh the C-D-D triple coincidence measurement (detection of part of the fragments) of CD_4, it was shown that D-C-D bond angle was rightly obtained. This result indicates the possibility of the local structure analysis by CEI.3 : The chirality of CD_4, which was distorted by the zero point vibrations, was analyzed demonstrating that the CEI method can distinguish the molecular chirality directly.4 : The new position sensitive detector, which combined the resistance substrate with the backgammon type electrode, was developed. The performance was evaluated, and it was shown that very high position and time resolution were obtained.The above results were announced in the scientific journals as papers, as well as in domestic and foreign conferences. And, the test equipment for collision experiments of fullerenes with highly charged ions was manufactured in order to analyze the dissociation process of the fullerenes from the new standpoint, and the preliminary time-of-flight analysis experiment of the product was carried out.