ELECTRON SPECTROSCOPIC STUDY ON ELECTRONIC STRUCTURES DEPENDENCE ON FULLERENE NETWORKS

有人提出了一种称为碳炔的线性碳链材料的存在，但由于其不稳定性，它们的性质尚未得到很好的研究。卡宾包括两种类型的化合物，即枯烯型和多炔型。为了研究碳炔的电子结构，测量了碳炔模型化合物的光电子能谱。用分子轨道（MO）方法计算了由于合成困难而无法测量光电子能谱的直链碳链化合物的电子结构，并对这些化合物的光电子能谱进行了很好的解释。累积多烯和聚炔类化合物的最高占据分子轨道（HOMO）都位于直链碳链上，而不是在引入以稳定分子的端基上。HOMO的结合能（电离势）随着链长的增加而降低。结果表明，在碳原子数相同的情况下，cumulene型化合物的HOMO能级和生成热均大于polyyene型化合物.测量了两种Ca @ C_（82）异构体的光电子能谱.与其它富勒烯一样，其光谱也表现出强度振荡。从头计算表明它们可能的结构。计算了从钙原子到富勒烯笼的电子转移量为2。对单壁碳纳米管和C_（60）包覆管的光电子发射进行了测量，但尚未得到可靠的数据。这些努力正在进行中。

An existence of linear carbon chain materials called Carbyne has been suggested, but their nature has not been investigated well because of its instability. Carbyne consists of two types compounds called cumulene type and polyyne type. In order to investigate the electronic structures of carbyne, photoelectron spectra of carbyne model compounds have been measured. Molecular orbital (MO) calculation has been performed to estimate the electronic structures of the linear carbon chain compounds of which photoelectron spectra could not be measured because of difficulty of their synthesis.The photoelectron spectra could be interpreted very well with the MO calculation. The highest occupied molecular orbital (HOMO) of both cumulene and polyyne types compounds resides on the linear carbon chain, not on the termination groups that were introduced to stabilize the molecules. The binding energy (ionization potential) of the HOMO decreases as the chain length increases. It was found that when the number of carbon atoms is the same the HOMO level and the heat of formation of cumulene type compounds are larger than those of polyyene type ones.Photoelectron spectra of calcium atom encapsulated fullerenes, two Ca@C82 isomers were measured. The spectra showed intensity oscillation as those of other fullerenes. ab initio calculation suggests their possible structure. The amounts of transferred electrons from the calcium atom to the fullerene cage was estimated to be two.Photoelectron emission measurements from single wall carbon nano tubes and C60 encapsulated tubes were tried, but reliable data have not been obtained yet. The attempts are under the way.