THEORETICAL INFRARED-SPECTRA OF SOME MODEL POLYCYCLIC AROMATIC-HYDROCARBONS - EFFECT OF IONIZATION

被引:145
作者
DEFREES, DJ
MILLER, MD
TALBI, D
PAUZAT, F
ELLINGER, Y
机构
[1] IBM CORP,DIV RES,ALMADEN RES CTR,SAN JOSE,CA 95120
[2] ECOLE NORMALE SUPER,EQUIPE ASTROCHIM QUANT,F-75231 PARIS 05,FRANCE
[3] OBSERV MEUDON,F-75005 PARIS,FRANCE
关键词
DUST; EXTINCTION; ISM; MOLECULES; MOLECULAR PROCESSES;
D O I
10.1086/172610
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
In order to test the hypothesis of ionized polycyclic aromatic hydrocarbons (PAHs) as possible carriers of the UIR bands, we realized a computational exploration on selected PAHs of small dimension in order to identify which changes ionization would induce on their IR spectra. In this study we performed ab initio calculations of the spectra of neutral and positively ionized naphthalene, anthracene, and pyrene. The results are significantly important. The frequencies in the cations are slightly shifted with respect to the neutral species, but no general conclusion can be reached from the three molecules considered. By contrast, the relative intensities of most vibrations are strongly affected by ionization, leading to a much better agreement between the calculated CH/CC vibration intensity ratios and those deduced from observations.
引用
收藏
页码:530 / 538
页数:9
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