Fluorescence excitation and emission spectra of polycyclic aromatic hydrocarbons at flame temperatures

1980 ◽  
Vol 76 (3) ◽  
pp. 485-489 ◽  
Author(s):  
D.S. Coe ◽  
J.I. Steinfeld
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Emission Spectra ◽  
Fluorescence Excitation ◽  
Polycyclic Aromatic

scholarly journals Spectroscopic Investigation of Fluorescence Quenching Agents. Part III: Effect of Solvent Polarity on the Selectivity of Nitromethane for Discriminating between Alternant versus Nonalternant Polycyclic Aromatic Hydrocarbons

1993 ◽  
Vol 47 (6) ◽  
pp. 715-722 ◽  
Author(s):  
Sheryl A. Tucker ◽  
William E. Acree ◽  
John C. Fetzer ◽  
Ronald G. Harvey ◽  
Mary J. Tanga ◽  
...  
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Solvent Polarity ◽  
Solvent Mixtures ◽  
Fluorescence Emission Spectra ◽  
Polycyclic Aromatic ◽  
Organic Nonelectrolyte ◽  
Emission Behavior

To better assess the applicability of nitromethane as a selective quenching agent for alternant versus nonalternant polycyclic aromatic hydrocarbons in HPLC, TLC, and HPTLC analysis, we measured the effect that it has on the fluorescence emission behavior of 96 different polycyclic aromatic hydrocarbons dissolved in binary toluene/acetonitrile solvent mixtures. Results of these measurements revealed that the “selective quenching” rule is obeyed for the vast majority of PAHs, with the coronene derivatives being the only major exceptions. Fluorescence emission spectra are also reported for benzo[g]chrysene, naphtho[2,3g]chrysene, 4 H-benzo[c]cyclopenta[mno]chrysene, dibenzo[ghi,mno]fluoranthene (commonly called corannulene), rubicene, diacenaphtho[l,2j:l‘,2'l]fluoranthene, 10-methyl-benzo[b]fluoranthene, 3-methoxybenzo[k]fluoranthene, and 3-hydroxybenzo[k]fluoranthene in organic nonelectrolyte solvents of varying polarity. Calculated emission intensity ratios failed to vary systematically with solvent polarity, and all nine of the aforementioned solutes were thus classified as nonprobe molecules.

scholarly journals Probing the size and charge of polycyclic aromatic hydrocarbons

2020 ◽  
Vol 494 (1) ◽  
pp. 642-664 ◽  
Author(s):  
A Maragkoudakis ◽  
E Peeters ◽  
A Ricca
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Intensity Ratio ◽  
Emission Spectra ◽  
Infrared Emission ◽  
Radiation Fields ◽  
Ionization Fraction ◽  
Ngc 7027 ◽  
Out Of Plane ◽  
Polycyclic Aromatic

ABSTRACT We present a new method to accurately describe the ionization fraction and the size distribution of polycyclic aromatic hydrocarbons (PAHs) within astrophysical sources. To this purpose, we have computed the mid-infrared emission spectra of 308 PAH molecules of varying sizes, symmetries, and compactness, generated in a range of radiation fields. We show that the intensity ratio of the solo CH out-of-plane bending mode in PAH cations and anions (referred to as the ‘11.0’ μm band, falling in the 11.0–11.3 μm region for cations and anions) to their 3.3 μm emission scales with PAH size, similarly to the scaling of the 11.2/3.3 ratio with the number of carbon atoms (NC) for neutral molecules. Among the different PAH emission bands, it is the 3.3 μm band intensity that has the strongest correlation with NC, and drives the reported PAH intensity ratio correlations with NC for both neutral and ionized PAHs. The 6.2/7.7 intensity ratio, previously adopted to track PAH size, shows no evident scaling with NC in our large sample. We define a new diagnostic grid space to probe PAH charge and size, using the (11.2 + 11.0)/7.7 and (11.2 + 11.0)/3.3 PAH intensity ratios, respectively. We demonstrate the application of the (11.2 + 11.0)/7.7–(11.2 + 11.0)/3.3 diagnostic grid for galaxies M82 and NGC 253, for the planetary nebula NGC 7027, and the reflection nebulae NGC 2023 and NGC 7023. Finally, we provide quantitative relations for PAH size determination depending on the ionization fraction of the PAHs and the radiation field they are exposed to.

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