论文标题
与苯基侧基多环芳烃的振动光谱研究
Study of vibrational spectra of polycyclic aromatic hydrocarbons with phenyl side group
论文作者
论文摘要
报道了在不同位置取代的苯基侧组的多环芳烃（PAHS）的计算研究。讨论了由于苯基取代，电离状态和分子大小而引起的红外光谱变化，并分析了苯基-PAHS对天体物理对象中中红外发射特征的可能贡献。与其他位置的取代相比，在第二位置上的结构苯基替代可以给出更稳定的物种。苯基-PAH在695和741 cm $^{ - 1} $（14.4和13.5 $μ$ M）附近表现出新的芳族带，这是由于五重奏C-H WAG的贡献，其与14.2和13.5 $ m $ m的次要特征相比，在几个天文学物体中观察到。就像在普通PAH中一样，C-C弹力振动模式（$ \ sim $ 1600 cm $^{ - 1} $）的中性强度可以忽略不计，但是所有苯基PAH的阳离子表现出明显强大的C-C组C-C伸展峰，接近B类6.2 $ 6.2 $ 6.2 $ $ m $ M $ M Atrophysical Bantothysical Bantothysical Bantothysical Bandropsical。在2-苯基苯乙烯中，是中性分子在6.2 $ $ m范围内表现出这种强大特征，以及其他与6.66和6.9 $ $ $ m的子功能匹配的特征，在某些晚期物体的天文光谱中观察到。在独奏位置的苯基侧基的替换使父pah的C-C伸展模式接近6.2 $ $ M $ M的天体物理带。结果表明，在空间中苯基-PAH和中等大小的紧凑型PAH的自下而上的苯基形成可能性，在富含碳的凉爽的室内壳中，苯基侧基。在对各种天体物理对象的中红外发射光谱进行建模时，需要考虑苯基-PAH。
Computational study of polycyclic aromatic hydrocarbons (PAHs) with phenyl side group substituted at different positions is reported. The infrared spectral variations due to the position of phenyl substitution, ionization state and the size of the molecules are discussed and possible contribution of phenyl-PAHs to the mid-infrared emission features from astrophysical objects is analyzed. Structurally phenyl group substitution at 2nd position gives more stable species compared to substitution at other positions. Phenyl-PAHs exhibit new aromatic bands near 695 and 741 cm$^{-1}$ (14.4 and 13.5 $μ$m), due to contribution from quintet C-H wag, that compare well with minor features at 14.2 and 13.5 $μ$m observed in several astrophysical objects. Just as in plain PAHs, the C-C stretch vibrational modes ($\sim$1600 cm$^{-1}$) have negligible intensity in neutrals, but the cations of all phenyl-PAHs exhibit significantly strong phenyl group C-C stretch peak close to class B type 6.2 $μ$m astrophysical band. In 2-phenylpyrene, it is the neutral molecule that exhibits this strong feature in the 6.2 $μ$m range along with other features that match with sub-features at 6.66 and 6.9 $μ$m, observed in astronomical spectra of some late type objects. The substitution of phenyl side group at solo position shifts the C-C stretch mode of parent PAH close to the region of 6.2 $μ$m astrophysical band. The results indicate possibility of phenyl-PAHs in space and the bottom-up formation of medium sized compact PAHs with phenyl side group in carbon rich cool circumstellar shells. Phenyl-PAHs need to be considered in modelling mid-infrared emission spectra of various astrophysical objects.
