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Record 26 of 406
Infrared spectra of substituted polycylic aromatic hydrocarbons
External Online Source: doi:10.1021/jp9731563
Author and Affiliation:
Langhoff, S. R.(NASA Ames Research Center, Moffett Field CA United States)
Bauschlicher, C. W. Jr
Hudgins, D. M.
Sandford, S. A.
Allamandola, L. J.
Abstract: Calculations are carried out using density functional theory (DFT) to determine the harmonic frequencies and intensities of 1-methylanthracene, 9-methylanthracene, 9-cyanoanthracene, 2-aminoanthracene, acridine, and their positive ions. The theoretical data are compared with matrix-isolation spectra for these species also reported in this work. The theoretical and experimental frequencies and relative intensities for the neutral species are in generally good agreement, whereas the positive ion spectra are only in qualitative agreement. Relative to anthracene, we find that substitution of a methyl or CN for a hydrogen does not significantly affect the spectrum other than to add the characteristic methyl C-H and C triple bond N stretches near 2900 and 2200 cm-1, respectively. However, addition of NH2 dramatically affects the spectrum of the neutral. Not only are the NH2 modes themselves strong, but this electron-withdrawing group induces sufficient partial charge on the ring to give the neutral molecule spectra characteristics of the anthracene cation. The sum of the absolute intensities is about four times larger for 2-aminoanthracene than those for 9-cyanoanthracene. Substituting nitrogen in the ring at the nine position (acridine) does not greatly alter the spectrum compared with anthracene.
Publication Date: Feb 26, 1998
Document ID:
20040088945
(Acquired Sep 07, 2004)
Subject Category: EXOBIOLOGY
Document Type: Journal Article
Publication Information: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment & general theory (ISSN 1089-5639); Volume 102; 9; 1632-46
Publisher Information: United States
Financial Sponsor: NASA Ames Research Center; Moffett Field CA United States
Description: In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: HYDROCARBONS; INFRARED SPECTRA; INFRARED SPECTROPHOTOMETERS; POLYCYCLIC AROMATIC HYDROCARBONS; SPECTROPHOTOMETRY; ANTHRACENE; COSMIC DUST; EXOBIOLOGY; EXTRATERRESTRIAL ENVIRONMENTS; HETEROCYCLIC COMPOUNDS; MODELS
Other Descriptors: POLYCYCLIC HYDROCARBONS, AROMATIC/ANALYSIS/CHEMISTRY; SPECTROPHOTOMETRY, INFRARED; ACRIDINES/CHEMISTRY; ANTHRACENES/ANALYSIS/CHEMISTRY; COMPARATIVE STUDY; COSMIC DUST/ANALYSIS; EXTRATERRESTRIAL ENVIRONMENT; MODELS, CHEMICAL; NASA CENTER ARC; NASA DISCIPLINE EXOBIOLOGY
Availability Source: Other Sources
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