Laboratory Studies on the Role of PAHs as DIB Carriers

Huisken, F.; Rouillé, Gaël; Steglich, Mathias; Carpentier, Y.; Jäger, Cornelia; Henning, Th.

doi:10.1017/s1743921313015974

Cited by 6 publications

(6 citation statements)

References 30 publications

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“…Because the maximum number of FAR of a helicene with experimental and theoretical absorbance spectral information available is 14 20 (see Table 1), the logarithmic trend established in Figure 2 is used in the following section to obtain the locations of p-bands for helicenes with 20−40 FAR. As discussed in the text surrounding Table 1, in the analysis of Figure 2, the locations of the p-bands for [10], [11], [12], [13], and [14]helicene provided by Birks and VanDer Donckt (as a note added like proof in advance of publication) in Obenland and Schmidt 20 with the maximum positive standard deviation (+0.06) are used to generate the maximum correlation coefficient of the resulting logarithmic trend, that is, close to one.…”

Section: Mathematical Methodsmentioning

confidence: 97%

“…The study of the molecules that absorb electromagnetic radiation in the interstellar medium, for example, the carriers of the diffuse interstellar bands, DIBs, is the subject of ongoing research in the astrophysical community. − Polycyclic aromatic hydrocarbons, PAHs, are considered potential carriers of the DIBs due to their verified presence in the interstellar medium and their striking stability in hostile atmospheres. , Numerous experimental and theoretical research efforts − have helped to understand better the spectroscopy of PAHs and its relationship with the DIBs. Despite these facts, the identifications of the DIBs using spectral information from PAHs or PAHs derivatives have yet to be established.…”

Section: Introductionmentioning

confidence: 99%

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The Helicenes: Potential Carriers of Diffuse Interstellar Bands

Oña-Ruales

Ruiz‐Morales

Alvarez-Ramírez

2021

ACS Earth Space Chem.

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In this work, the helicenes are postulated as potential carriers of the diffuse interstellar bands, DIBs. The helicenes are nonplanar cata-condensed molecules structurally related to the polyacenes, and polyacenes have been already proposed as conceivable carriers of the DIBs. In here, the possible identity of the carrier of the DIB at 4502 Å is studied and potentially identified as a cata-condensed helicene using spectroscopic, statistical, and stability methods. First, statistic and spectroscopic information allow the fitting of the regression equation that governs the variation of the location of the published absorbance p-bands as a function of the number of fused aromatic rings (nFAR) for planar and helical cata-condensed polycyclic aromatic hydrocarbons with 1−14 FAR, and the application of this equation to establish the identity of the possible carrier of the 4502 Å DIB, that is, [26]helicene (C 106 H 56 ). The difference between the calculated location of the p-band from the fitted equation and the DIB location under study is equal to 0.21%. Subsequently, an aromaticity argument demonstrates the presence of π-delocalizing benzene effect in helicenes with the general formula C 2+4N H 2N+4 , for example, [26]helicene, that would theoretically provide supplementary stability to the molecule to justify its occurrence. Finally, a feasible mechanism of formation of helicenes in the interstellar medium is proposed that involves successive additions of n-butane units to a phenanthrene moiety. To the best of our knowledge, this is the first report about the possible presence of cata-condensed helical molecules in the DIBs and the first study that theorizes that [26]helicene is the possible carrier of the DIB at 4502 Å.

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Section: Mathematical Methodsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

The Helicenes: Potential Carriers of Diffuse Interstellar Bands

Oña-Ruales

Ruiz‐Morales

Alvarez-Ramírez

2021

ACS Earth Space Chem.

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“…The absorption measurements at seven wavelengths allowed us to evaluate AAEs in different wavelength intervals. The high optical band gap energies (Menon et al 2019) and absorption spectra (Huisken et al 2013) associated with non-refractory PAHs observed in the AMS (mainly PAHs with molecular masses of 202-300 Da) suggested that the non-refractory components that were removed in the TD would have only a minor contribution to absorption at wavelengths longer than 660 nm. Therefore, AAEs were evaluated in two wavelength intervals: the full 370-950 nm wavelength interval (AAE 370-950nm ) and for the 660-950 nm wavelength interval (AAE 660-950nm ).…”

Section: Aae In Different Wavelength Intervalsmentioning

confidence: 99%

Characteristics of BrC and BC emissions from controlled diffusion flame and diesel engine combustion

Malmborg

Eriksson

Gren

et al. 2021

Aerosol Science and Technology

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Constraining the climate impact of particulate brown carbon (BrC) will require identification of formation mechanisms and isolation of its different components to allow for source apportionment. For fresh combustion aerosols, the light absorption characteristics and the Absorption Ångstrom Exponent (AAE) are principally controlled by the combustion conditions in which the particles formed and evolved. We investigated the influence of combustion temperatures on the BrC or black carbon (BC) emission characteristics for a miniCAST soot generator (propane fuel) and a modern heavyduty diesel engine (petroleum diesel and two renewable diesel fuels). Changes in the AAE, mass spectral signatures, and thermal-optical characteristics were studied. We show that changing operating parameters to gradually reduce the combustion temperatures in these two fundamentally different combustion devices result in a regression from BC dominated to BrC dominated particle emissions. The regression towards BrC was associated with: 1) an increasing mass fraction of particulate non-refractory polycyclic aromatic hydrocarbons (PAHs), 2) an increasing fraction of refractory organic carbon, 3) more curved soot nanostructures and shorter fringe lengths, and 4) increased signal from (refractory) large carbon fragments in IR laser-vaporization aerosol mass spectra. Based on these results we argue that fresh BrC dominated combustion aerosols are attributed to primary emissions from low temperature combustion, highlighting the influence of refractory constituents and soot nanostructure. Higher temperatures favor the growth of conjugated polyaromatic structures in the soot, a progression hypothesized to control the evolution from BrC to BC character of the emitted aerosols.

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“…9,10 Leaving aside their threat to humans health, 11 in the last years they have become highly relevant in industrial applications such as the production of dyes and pigments and pharmaceuticals 12,13 due to their photostability and photophysical properties. 14,15 These compounds have also been found to be a key piece in the understanding the chemistry of the interstellar medium. 16…”

Section: Introductionmentioning

confidence: 99%