Infrared vibrational and electronic transitions in the dibenzopolyacene family

Mattioda, A. L.; Bauschlicher, Charles W.; Bregman, J.; Hudgins, Douglas M.; Allamandola, Louis J.; Ricca, Alessandra

doi:10.1016/j.saa.2014.04.017

Cited by 12 publications

(9 citation statements)

References 42 publications

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“…A slight shift of a few cm -1 also appears for the three components after irradiation typical of a change in the chemical environment of the C-H bonds. A similar positive shift has been observed in the C-H stretching signatures of series of molecules, either through steric effects increasing hydrogen-hydrogen interactions within the material 25 or by the substitution of the adjacent carbon by a nitrogen atom 26 . The interactions with both an opposing hydrogen atom or an adjacent nitrogen lone electron pair hinder the C-H stretch, which requires more energy to occur.…”

Section: Resultssupporting

confidence: 67%

The evolution of Titan’s high-altitude aerosols under ultraviolet irradiation

et al. 2018

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The Cassini-Huygens space mission revealed that Titan's thick brownish haze is initiated high in the atmosphere at about 1000 km of altitude, before a slow transportation down to the surface. Close to the surface at altitudes below 130 km, the Huygens probe provided information on the chemical composition of the haze. So far we do not have insights on a possible photochemical evolution of the aerosols composing the haze during their descent.We address here this atmospheric aerosol aging process, simulating in the laboratory how solar vacuum-ultraviolet (VUV) irradiation affects the aerosol optical properties as probed by infrared spectroscopy. An important evolution is found, which could explain the apparent contradiction between the nitrogen-poor infrared spectroscopic signature observed by Cassini below 600 km of altitude in Titan's atmosphere, and a high nitrogen content as measured by the Aerosol Collector and Pyroliser of Huygens probe at the surface of Titan.

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Section: Resultssupporting

confidence: 67%

The evolution of Titan’s high-altitude aerosols under ultraviolet irradiation

et al. 2018

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“…PAHs with side groups have been assigned molecular UIDs ranging from 775 to 812 (Bauschlicher 2016). The naphtho-benzo-pyrene anion from the study of Mattioda et al (2014) that was computed using a 6-31G * basis set was added with molecular UID 813 and hexacene, heptacene, and octacene have molecular UIDs 814 to 822; the IR spectra for the other species described in Mattioda et al (2014) were computed using the B3LYP/4-31G approach and were already in the database. PAHs with molecular UIDs from 823 to 828 were some unpublished C 54 H 18 species; one had an extra hydrogen added, while the others had one or more five-membered rings.…”

Section: Added Species and Compositionmentioning

confidence: 99%

The NASA Ames PAH IR Spectroscopic Database: Computational Version 3.00 with Updated Content and the Introduction of Multiple Scaling Factors

Bauschlicher

Ricca

Boersma

et al. 2018

ApJS

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Version 3.00 of the library of computed spectra in the NASA Ames PAH IR Spectroscopic Database (PAHdb) is described. Version 3.00 introduces the use of multiple scale factors, instead of the single scaling factor used previously, to align the theoretical harmonic frequencies with the experimental fundamentals. The use of multiple scale factors permits the use of a variety of basis sets; this allows new PAH species to be included in the database, such as those containing oxygen, and yields an improved treatment of strained species and those containing nitrogen. In addition, the computed spectra of 2439 new PAH species have been added. The impact of these changes on the analysis of an astronomical spectrum through database-fitting is considered and compared with a fit using Version 2.00 of the library of computed spectra. Finally, astronomical constraints are defined for the PAH spectral libraries in PAHdb.

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“…Due to the involatile nature of PAHs, two dominant techniques are used to obtain the IR spectrum: high-temperature gas-phase spectroscopy or low-temperature matrix-isolation spectroscopy. [10][11][12][13][14][15][16][17] Attempts to extrapolate these experimental data to astrophysically relevant conditions are complicated by temperature effects in the former and matrix-interaction effects in the latter. High-resolution, low-temperature gasphase spectra have been taken previously, but only for a handful of species and only in the C-H stretching region (2950-3150 cm −1 , 3 µm).…”

Section: Introductionmentioning

confidence: 99%

The anharmonic quartic force field infrared spectra of five non-linear polycyclic aromatic hydrocarbons: Benz[a]anthracene, chrysene, phenanthrene, pyrene, and triphenylene

Mackie

Candian

Huang

et al. 2016

The Journal of Chemical Physics

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The anharmonic quartic force field infrared spectra of three polycyclic aromatic hydrocarbons: Naphthalene, anthracene, and tetracene J. Chem. Phys. 143, 224314224314 (2015); 10.1063/1.4936779 THE JOURNAL OF CHEMICAL PHYSICS 145, 084313 (2016) The anharmonic quartic force field infrared spectra of five non The study of interstellar polycyclic aromatic hydrocarbons (PAHs) relies heavily on theoretically predicted infrared spectra. Most earlier studies use scaled harmonic frequencies for band positions and the double harmonic approximation for intensities. However, recent high-resolution gas-phase experimental spectroscopic studies have shown that the harmonic approximation is not sufficient to reproduce experimental results. In our previous work, we presented the anharmonic theoretical spectra of three linear PAHs, showing the importance of including anharmonicities into the theoretical calculations. In this paper, we continue this work by extending the study to include five non-linear PAHs (benz[a]anthracene, chrysene, phenanthrene, pyrene, and triphenylene), thereby allowing us to make a full assessment of how edge structure, symmetry, and size influence the effects of anharmonicities. The theoretical anharmonic spectra are compared to spectra obtained under matrix isolation low-temperature conditions, low-resolution, high-temperature gas-phase conditions, and high-resolution, low-temperature gas-phase conditions. Overall, excellent agreement is observed between the theoretical and experimental spectra although the experimental spectra show subtle but significant differences. Published by AIP Publishing.[http://dx

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Infrared vibrational and electronic transitions in the dibenzopolyacene family

Cited by 12 publications

References 42 publications

The evolution of Titan’s high-altitude aerosols under ultraviolet irradiation

The evolution of Titan’s high-altitude aerosols under ultraviolet irradiation

The NASA Ames PAH IR Spectroscopic Database: Computational Version 3.00 with Updated Content and the Introduction of Multiple Scaling Factors

The anharmonic quartic force field infrared spectra of five non-linear polycyclic aromatic hydrocarbons: Benz[a]anthracene, chrysene, phenanthrene, pyrene, and triphenylene

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