一种大分子多环芳烃：六-正-六苯并蔻（C42H18）的光谱
The optical spectrum of a large isolated polycyclic aromatic hydrocarbon: hexa-peri-hexabenzocoronene, C42H18
摘要：
报道了一种大到足以在星际介质物理条件下存活的孤立多环芳烃的第一个光谱。用共振双色双光子电离光谱在4080-4530埃范围内观测到全苯环多环芳烃六-正-六苯并蔻的第一电子跃迁振动带。在4264埃处最强的特征估计具有f=1.4x10^-3的振子强度，这使得这种多环芳烃的星际丰度上限为4x10^12 cm^-2，最大约占星际碳的0.02%。这项研究开辟了可能性，严格测试中性多环芳烃作为载体的弥漫星际带在不久的将来。
英文摘要：
The first optical spectrum of an isolated polycyclic aromatic hydrocarbon large enough to survive the photophysical conditions of the interstellar medium is reported. Vibronic bands of the first electronic transition of the all benzenoid polycyclic aromatic hydrocarbon hexa-peri-hexabenzocoronene were observed in the 4080-4530 Angstrom range by resonant 2-color 2-photon ionization spectroscopy. The strongest feature at 4264 Angstrom is estimated to have an oscillator strength of f=1.4x10^-3, placing an upper limit on the interstellar abundance of this polycyclic aromatic hydrocarbon at 4x10^12 cm^-2, accounting for a maximum of ~0.02% of interstellar carbon. This study opens up the possibility to rigorously test neutral polycyclic aromatic hydrocarbons as carriers of the diffuse interstellar bands in the near future.
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