Polycyclic aromatic hydrocarbons (PAH) and their derivatives, including protonated and cationic species, are suspected to be carriers of the unidentified infrared (UIR) emission bands observed from the galactic and extragalactic sources. We extended our investigations of infrared (IR) spectra of protonated planar PAH to a nonplanar PAH, corannulene (C₂₀H₁₀), which is regarded as a fragment of a fullerene, C₆₀. The protonated corannulene H⁺C₂₀H₁₀ was produced on bombarding a mixture of corannulene and para-hydrogen (p-H₂) with electrons during deposition at 3.2 K. During maintenance of the electron-bombarded matrix in darkness the intensities of IR lines of protonated corannulene decreased because of neutralization by electrons that were slowly released from the trapped sites. The observed lines were classified into two groups according to their responses to secondary irradiation at 365 nm. Eighteen lines in one group are assigned to the lowest-energy species among five possible isomers, hub-H⁺C₂₀H₁₀, and 17 in another group to rim-H⁺C₂₀H₁₀, the species of second lowest energy. Spectral assignments were derived based on a comparison of the observed spectra with those predicted with the B3PW91/6-311++G(2d,2p) method. The observed IR spectrum of hub-H⁺C₂₀H₁₀ resembles several bands of the Class-A UIR bands.

中文翻译：

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固体对氢中质子化氢化邻苯二酚H ⁺ C ₂₀ H _10的红外光谱及其对星际不明红外波段的潜在贡献

多环芳烃（PAH）及其衍生物（包括质子化和阳离子型）被怀疑是从银河和银河外源观察到的未确定的红外（UIR）发射带的载体。我们将质子化平面PAH的红外（IR）光谱研究扩展到了非平面PAH氢化可仑烯（C ₂₀ H ₁₀），后者被视为富勒烯C ₆₀的片段。质子化的碗烯ħ ⁺ Ç ₂₀ ħ ₁₀被上轰击碗烯的混合物和所产生的对-氢（p -H ₂）在3.2 K的沉积过程中带有电子。在黑暗中维持电子轰击基体的过程中，由于电子的中和作用从被俘获的位置缓慢释放，质子化的环戊烯的IR线的强度降低了。根据观察到的谱线对365 nm二次辐照的响应，将其分为两组。一组中的18条线被分配为五个可能的异构体中最低能量的物种，中心是-H ⁺ C ₂₀ H ₁₀，另一组中的17条是边缘-H ⁺ C ₂₀ H ₁₀，第二低能量的物种。光谱分配是根据观察到的光谱与B3PW91 / 6-311 ++ G（2d，2p）方法预测的光谱进行比较得出的。观察到的-H ⁺ C ₂₀ H ₁₀中心的红外光谱类似于A类UIR波段的几个波段。