Arakawa R, Kobayashi M, Nishimura T
Department of Applied Chemistry, Kansai University, Suita, Osaka 564-8680, Japan.
J Mass Spectrom. 2000 Feb;35(2):178-82. doi: 10.1002/(SICI)1096-9888(200002)35:2<178::AID-JMS927>3.0.CO;2-S.
High-energy collision-induced dissociation (CID) experiments on polycyclic aromatic hydrocarbons (PAHs) having 2-6 rings, naphthalene, anthracene, phenanthrene, fluoranthene, pyrene and coronene, were performed, and the relative abundances of their fragment ions were investigated as a function of collision energy. The results revealed that the PAHs except naphthalene showed a bimodal-type distribution of positive fragmentation ions, which is closely similar to the fragment-ion distribution reported for the CID of three-dimensional fullerene, C(60)(+) and C(70)(+). The three-ring isomers of anthracene and phenanthrene and the four-ring isomers of fluoranthene and pyrene can be distinguishable in their spectra under an electron ionization energy of 70 eV, but the high-energy CID spectra of the three- and four-ring isomers were almost identical. The fragmentation corresponding to fragment ions in the low-mass region of the bimodal CID spectra could be interpreted by the simple statistical model that fragment ions are formed by random evaporation from the molecular ions after a considerable structural rearrangement, 'phase transition', occurring at some high-energy state.
对含有2至6个环的多环芳烃（PAHs），即萘、蒽、菲、荧蒽、芘和蔻进行了高能碰撞诱导解离（CID）实验，并研究了其碎片离子的相对丰度随碰撞能量的变化。结果表明，除萘以外的多环芳烃呈现出双峰型正碎片离子分布，这与报道的三维富勒烯C(60)(+)和C(70)(+)的CID碎片离子分布非常相似。蒽和菲的三环异构体以及荧蒽和芘的四环异构体在70 eV电子电离能下的光谱中可以区分，但三环和四环异构体的高能CID光谱几乎相同。双峰CID光谱低质量区域中对应碎片离子的碎裂可以用简单的统计模型来解释，即碎片离子是在分子离子经历了相当程度的结构重排，即在某个高能态发生“相变”之后，通过随机蒸发形成的。
