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首页> 外文期刊>Spectrochimica acta, Part A. Molecular and biomolecular spectroscopy >Hydrogenation of polycyclic aromatic hydrocarbons as a factor affecting the cosmic 6.2 micron emission band
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Hydrogenation of polycyclic aromatic hydrocarbons as a factor affecting the cosmic 6.2 micron emission band

机译：多环芳烃的加氢是影响宇宙6.2微米发射带的因素

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摘要

While many of the characteristics of the cosmic unidentified infrared (UIR) emission bands observed for interstellar and circumstellar sources within the Milky Way and other galaxies, can be best attributed to vibrational modes of the variants of the molecular family known as polycyclic aromatic hydrocarbons (PAH), there are open questions that need to be resolved. Among them is the observed strength of the 6.2 micron (1600 cm(-1)) band relative to other strong bands, and the generally low strength for measurements in the laboratory of the 1600 cm(-1) skeletal vibration band of many specific neutral PAH molecules. Also, experiments involving laser excitation of some gas phase neutral PAH species while producing long lifetime state emission in the 3.3 micron (3000 cm(-1)) spectral region, do not result in significant 6.2 micron (1600 cm(-1)) emission. A potentially important variant of the neutral PAH species, namely hydrogenated-PAM (H-N-PAH) which exhibit intriguing spectral correlation with interstellar and circumstellar infrared emission and the 2175 Angstrom extinction feature, may be a factor affecting the strength of 6.2 micron emission. These species are hybrids of aromatic and cycloalkane structures. Laboratory infrared absorption spectroscopy augmented by density function theory (DFT) computations of selected partially hydrogenated-PAM molecules, demonstrates enhanced 6.2 micron (1600 cm(-1)) region skeletal vibration mode strength for these molecules relative to the normal PAH form. This along with other factors such as ionization or the incorporation of nitrogen or oxygen atoms could be a reason for the strength of the cosmic 6.2 micron (1600 cm(-1)) feature. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 28]
机译：虽然在银河系和其他星系中观测到的星际和星际源的宇宙未识别红外（UIR）发射带的许多特征，可以最好地归因于称为多环芳香烃（PAH）的分子家族变体的振动模式），还有一些未解决的问题需要解决。其中包括相对于其他强谱带观察到的6.2微米（1600 cm（-1））谱带的强度，以及实验室中许多特定中性的1600 cm（-1）骨骼振动谱带的测量强度通常较低。 PAH分子。此外，涉及某些气相中性PAH物种的激光激发，同时在3.3微米（3000 cm（-1））光谱范围内产生长寿命状态发射的实验，不会导致显着的6.2微米（1600 cm（-1））发射。 。中性PAH物种的潜在重要变体，即氢化PAM（H-N-PAH）与星际和星际红外辐射以及2175埃的消光特征表现出令人感兴趣的光谱相关性，可能是影响6.2微米发射强度的因素。这些物质是芳族和环烷结构的杂物。实验室红外吸收光谱法通过对选定的部分氢化的PAM分子进行密度函数理论（DFT）计算来增强，证明这些分子相对于正常的PAH形式具有增强的6.2微米（1600 cm（-1））区域骨架振动模式强度。这连同其他因素，例如电离或氮或氧原子的掺入，可能是宇宙6.2微米（1600 cm（-1））功能强度的原因。 （C）2001 Elsevier Science B.V.保留所有权利。 [参考：28]

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