scholarly journals Anharmonicity and the infrared emission spectrum of highly excited polycyclic aromatic hydrocarbons

2018 ◽  
Vol 618 ◽  
pp. A49 ◽  
Author(s):  
Tao Chen ◽  
Cameron Mackie ◽  
Alessandra Candian ◽  
Timothy J. Lee ◽  
Alexander G. G. M. Tielens
Keyword(s):  
Experimental Data ◽  
Polycyclic Aromatic Hydrocarbons ◽  
Ir Spectra ◽  
Gas Phase ◽  
Aromatic Hydrocarbons ◽  
Temperature Effects ◽  
Infrared Emission ◽  
Polycyclic Aromatic ◽  
Vibrational Bands ◽  
Combination Bands

Aims. Infrared (IR) spectroscopy is a powerful tool to study molecules in space. A key issue in such analyses is understanding the effect that temperature and anharmonicity have on different vibrational bands, and thus interpreting the IR spectra for molecules under various conditions. Methods. We combined second order vibrational perturbation theory and the Wang-Landau random walk technique to produce accurate IR spectra of highly excited polycyclic aromatic hydrocarbons. We fully incorporated anharmonic effects, such as resonances, overtones, combination bands, and temperature effects. Results. The results are validated against experimental results for the pyrene molecule (C16H10). In terms of positions, widths, and relative intensities of the vibrational bands, our calculated spectra are in excellent agreement with gas-phase experimental data.

scholarly journals The Infrared Emission Features and Polycyclic Aromatic Hydrocarbons

1989 ◽  
Vol 135 ◽  
pp. 129-140
Author(s):  
L. J. Allamandola
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Related Species ◽  
Infrared Emission ◽  
Polycyclic Aromatic

The infrared evidence which supports the PAH hypothesis is briefly summarized. Rather than presenting a general discussion of these assignments, this paper focuses on the spectroscopic issues raised by recent observational and experimental developments. These issues include: the position and profile of the “1310” cm−1(“7.7” μm) feature, the position and intensities of the bands in the 910-710 cm−1(11-14 μm) region, the newly detected 1900 cm−1(5.3 μm) band, and the spatial and spectral variations in the 3000 cm−1(3 μm) region as well as in the 12 and 25 μm IRAS bands. It is concluded that the infrared evidence for interstellar PAHs and PAH-related species is compelling.

scholarly journals Study of passive sampling of polycyclic aromatic hydrocarbons in gas phase using Amberlite XAD resins as filling materials of semipermeable membranes

2013 ◽  
Vol 110 ◽  
pp. 494-500 ◽  
Author(s):  
Luis Gustavo T. dos Reis ◽  
Daniel Gallart-Mateu ◽  
Wagner F. Pacheco ◽  
Agustín Pastor ◽  
Miguel de la Guardia ◽  
...  
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Gas Phase ◽  
Aromatic Hydrocarbons ◽  
Passive Sampling ◽  
Semipermeable Membranes ◽  
Filling Materials ◽  
Polycyclic Aromatic ◽  
Xad Resins

scholarly journals Variability of polycyclic aromatic hydrocarbons and their oxidative derivatives in wintertime Beijing, China

2019 ◽  
Vol 19 (13) ◽  
pp. 8741-8758 ◽  
Author(s):  
Atallah Elzein ◽  
Rachel E. Dunmore ◽  
Martyn W. Ward ◽  
Jacqueline F. Hamilton ◽  
Alastair C. Lewis
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Gas Phase ◽  
Aromatic Hydrocarbons ◽  
Total Concentration ◽  
Diagnostic Ratios ◽  
Strong Positive Correlation ◽  
Night Time ◽  
Naphthalic Anhydride ◽  
Positive Correlation ◽  
Polycyclic Aromatic

Abstract. Ambient particulate matter (PM) can contain a mix of different toxic species derived from a wide variety of sources. This study quantifies the diurnal variation and nocturnal abundance of 16 polycyclic aromatic hydrocarbons (PAHs), 10 oxygenated PAHs (OPAHs) and 9 nitrated PAHs (NPAHs) in ambient PM in central Beijing during winter. Target compounds were identified and quantified using gas chromatography–time-of-flight mass spectrometry (GC-Q-ToF-MS). The total concentration of PAHs varied between 18 and 297 ng m−3 over 3 h daytime filter samples and from 23 to 165 ng m−3 in 15 h night-time samples. The total concentrations of PAHs over 24 h varied between 37 and 180 ng m−3 (mean: 97±43 ng m−3). The total daytime concentrations during high particulate loading conditions for PAHs, OPAHs and NPAHs were 224, 54 and 2.3 ng m−3, respectively. The most abundant PAHs were fluoranthene (33 ng m−3), chrysene (27 ng m−3), pyrene (27 ng m−3), benzo[a]pyrene (27 ng m−3), benzo[b]fluoranthene (25 ng m−3), benzo[a]anthracene (20 ng m−3) and phenanthrene (18 ng m−3). The most abundant OPAHs were 9,10-anthraquinone (18 ng m−3), 1,8-naphthalic anhydride (14 ng m−3) and 9-fluorenone (12 ng m−3), and the three most abundant NPAHs were 9-nitroanthracene (0.84 ng m−3), 3-nitrofluoranthene (0.78 ng m−3) and 3-nitrodibenzofuran (0.45 ng m−3). ∑PAHs and ∑OPAHs showed a strong positive correlation with the gas-phase abundance of NO, CO, SO2 and HONO, indicating that PAHs and OPAHs can be associated with both local and regional emissions. Diagnostic ratios suggested emissions from traffic road and coal combustion were the predominant sources of PAHs in Beijing and also revealed the main source of NPAHs to be secondary photochemical formation rather than primary emissions. PM2.5 and NPAHs showed a strong correlation with gas-phase HONO. 9-Nitroanthracene appeared to undergo a photodegradation during the daytime and showed a strong positive correlation with ambient HONO (R=0.90, P < 0.001). The lifetime excess lung cancer risk for those species that have available toxicological data (16 PAHs, 1 OPAH and 6 NPAHs) was calculated to be in the range 10−5 to 10−3 (risk per million people ranges from 26 to 2053 cases per year).

Gas phase adiabatic electron affinities of cyclopenta-fused polycyclic aromatic hydrocarbons

2008 ◽  
Vol 454 (1-3) ◽  
pp. 30-35 ◽  
Author(s):  
Petar D. Todorov ◽  
Carola Koper ◽  
Joop H. van Lenthe ◽  
Leonardus W. Jenneskens
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Gas Phase ◽  
Aromatic Hydrocarbons ◽  
Electron Affinities ◽  
Polycyclic Aromatic
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