Polycyclic Aromatic Hydrocarbons and the Diffuse Interstellar Bands: A Survey

Salama, Farid; Галазутдинов, Г. А.; Krełowski, J.; Allamandola, Louis J.; Мусаев, Ф. А.

doi:10.1086/307978

Cited by 188 publications

(131 citation statements)

References 36 publications

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“…We further detect another weak band at 473 nm, which is also visible in the neon-matrix spectrum (44), even if unlisted in this paper, which would be the D 9 ←− D 0 , calculated to be at 478 nm with an oscillator strength f = 9.2 × 10 −3 . Finally, the band detected at 502 nm in the neon-matrix spectrum would then be the D 5 ←− D 0 , calculated to be at 491 nm with an oscillator strength f = 7.6 × 10 −3 , even if at least part of this band could be due to a coincident very strong band in benzo(g,h,i)perylene (40), which could be formed in the matrix experiment by fragmentation of coronene. The comparison between the two theoretical calculations, obtained with and without the D 6h symmetry constraint, and corresponding to very close geometries, show the sensitivity of band positions and intensities to the conformation of the molecule.…”

Section: The Pyrene Cation (C 16 H 10 + )mentioning

confidence: 99%

Visible photodissociation spectroscopy of PAH cations and derivatives in the PIRENEA experiment

et al. 2010

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The electronic spectra of gas-phase cationic polycyclic aromatic hydrocarbons (PAHs), trapped in the Fourier Transform Ion Cyclotron Resonance cell of the PIRENEA experiment, have been measured by multiphoton dissociation spectroscopy in the 430-480 nm spectral range using the radiation of a mid-band optical parametric oscillator laser. We present here the spectra recorded for different species of increasing size, namely the pyrene cation (C 16 H 10 + ), the 1-methylpyrene cation (CH 3 − C 16 H 9 + ), the coronene cation (C 24 H 12 + ), and its dehydrogenated derivative C 24 H 10 + . The experimental results are interpreted with the help of time-dependent density functional theory calculations and analysed using spectral information on the same species obtained from matrix isolation spectroscopy data. A kinetic Monte Carlo code has also been used, in the case of pyrene and coronene cations, to estimate the absorption crosssections of the measured electronic transitions. Gas-phase spectra of highly reactive species such as dehydrogenated PAH cations are reported for the first time.

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Section: The Pyrene Cation (C 16 H 10 + )mentioning

confidence: 99%

Visible photodissociation spectroscopy of PAH cations and derivatives in the PIRENEA experiment

et al. 2010

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“…The vibrational excitation would result from the absorption of UV or visible photons. Ionized PAHs absorb in the visible and near-IR and are also potential carries of the DIBs (Salama et al 1996(Salama et al , 1999. A large effort is devoted to laboratory measurements of the UV-visible-NIR absorption spectra of PAHs (see, e.g., Ruiterkamp et al 2002).…”

Section: Diffuse Interstellar Bandsmentioning

confidence: 99%

Fullerenes and Buckyonions in the Interstellar Medium

Iglesias‐Groth

2004

ApJ

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We show that photoabsorption by fullerenes and buckyonions (multishell fullerenes) explain the shape, width, and peak energy of the most prominent feature of interstellar absorption, the UV bump at 2175 . The predicted A optical and near-infrared transitions for these molecules also offer a potential explanation for the long-standing problem of the identity of the diffuse interstellar bands. The implied ubiquitous distribution of fullerenes may also account for the anomalous galactic microwave emission detected by cosmic microwave background experiments. Comparing theoretical cross sections and astronomical data, we estimate a density of fullerenes in the diffuse interstellar medium of 0.1-0.2 parts per million, consistent with the findings in meteorites. Fullerenebased molecules appear to be a major carbon reservoir in the interstellar medium.

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“…Hundreds of DIBs have been found so far and many carriers have been proposed. Polycyclic aromatic hydrocarbons (PAHs) have been suggested by Salama et al (1999), Zhou et al (2006) and Leidlmair et al (2011), Kroto dalyabaron@mail.tau.ac.il † dovi@tau.ac.il the full width half maximum (FWHM) of the 6196Å DIB and the rotational temperature of the C2 molecule. Weselak et al (2014) found a correlation between the 4964Å DIB and CH and between the 6916Å DIB and CH+.…”

Section: Introductionmentioning

confidence: 99%

Using Machine Learning to classify the diffuse interstellar bands

Baron

Poznanski

Watson

et al. 2015

Monthly Notices of the Royal Astronomical Society

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Using over a million and a half extragalactic spectra from the Sloan Digital Sky Survey we study the correlations of the Diffuse Interstellar Bands (DIBs) in the Milky Way. We measure the correlation between DIB strength and dust extinction for 142 DIBs using 24 stacked spectra in the reddening range E(B − V ) < 0.2, many more lines than ever studied before. Most of the DIBs do not correlate with dust extinction. However, we find 10 weak and barely studied DIBs with correlations that are higher than 0.7 with dust extinction and confirm the high correlation of additional 5 strong DIBs. Furthermore, we find a pair of DIBs, 5925.9Å and 5927.5Å, which exhibits significant negative correlation with dust extinction, indicating that their carrier may be depleted on dust. We use Machine Learning algorithms to divide the DIBs to spectroscopic families based on 250 stacked spectra. By removing the dust dependency we study how DIBs follow their local environment. We thus obtain 6 groups of weak DIBs, 4 of which are tightly associated with C 2 or CN absorption lines.

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Polycyclic Aromatic Hydrocarbons and the Diffuse Interstellar Bands: A Survey

Cited by 188 publications

References 36 publications

Visible photodissociation spectroscopy of PAH cations and derivatives in the PIRENEA experiment

Visible photodissociation spectroscopy of PAH cations and derivatives in the PIRENEA experiment

Fullerenes and Buckyonions in the Interstellar Medium

Using Machine Learning to classify the diffuse interstellar bands

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