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           transition of benzo[g,h,i]perylene in supersonic jets and rare gas matrices

Rouillé, Gaël; Arold, M.; Staicu, Angela; Krasnokutski, Serge A.; Huisken, F.; Henning, Th.; Tan, Xiaofeng; Salama, Farid

doi:10.1063/1.2727467

Cited by 25 publications

(31 citation statements)

References 42 publications

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“…The wavelength positions and widths are from our CRDS experiments, except for hexabenzocoronene, for which the wavelength position in the gas phase was extrapolated from (b) an upper limit of the column density has been calculated assuming a detection limit with an equivalent width of 1 mÅ; (c) Staicu et al (2004); (d) Rouillé et al (2010); (e) Rouillé et al (2004); ( f ) Staicu et al (2008); (g) Rouillé et al (2007); (h) extrapolated from Ne and Ar matrix measurements (Rouillé et al 2009b); (i) calculated for Ne matrix spectra. matrix measurements (cf.…”

Section: Determination Of Absolute Absorption Cross Sections For Supementioning

confidence: 99%

“…From the various PAHs studied in our laboratory, we have selected six species revealing prominent absorption features in the 3050−3850 Å region, and for which CRDS spectra are available (Rouillé et al , 2007Staicu et al 2004Staicu et al , 2008. In the order of increasing size, these molecules are anthracene, phenanthrene, pyrene, 2,3-benzofluorene, benzo[ghi]perylene, and hexa-peri-hexabenzocoronene (hexabenzocoronene in the following).…”

Section: Laboratory Datamentioning

confidence: 99%

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Abundances of PAHs in the ISM: confronting observations with experimental results

Gredel

Carpentier

Rouillé

et al. 2011

A&A

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104

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Context. The identification of the carriers of the diffuse interstellar bands (DIBs) is the longest standing problem in the study of the interstellar medium. Here we present recent UV laboratory spectra of various polycyclic aromatic hydrocarbons (PAHs) and explore the potential of these molecules as carriers of the DIBs. Whereas, in the near IR range, the PAHs exhibit vibrational bands that are not molecule-specific, their electronic transitions occurring in the UV/vis provide characteristic fingerprints. The comparison of laboratory spectra calibrated in intensity with high signal-to-noise observational data in the UV enables us to establish new constraints on PAH abundances. Aims. From a detailed comparison of the gas-phase and Ne-matrix absorption spectra of anthracene, phenanthrene, pyrene, 2,3-benzofluorene, benzo[ghi]perylene, and hexabenzocoronene with new interstellar spectra, we aim to infer the abundance of these PAHs in the interstellar medium. Methods. We present spectra of PAHs measured at low temperature in the gas phase and in an Ne matrix, and present methods to derive absolute absorption cross sections for the matrix and gas phase spectra. We have obtained high signal to noise (S/N > 100) absorption spectra toward five lines of sight with reddenings of E B−V = 1−1.6 mag. The spectra cover the 3050−3850 Å wavelength region where the PAHs studied here show prominent absorption features. Results. From the observations, we infer upper limits in the fractional abundances of the PAHs studied here. Upper limits in the column densities of anthracene of 0.8−2.8 × 10 12 cm −2 and of pyrene and 2,3-benzofluorene ranging from 2−8 × 10 12 cm −2 are inferred. Upper limits in the column densities of benzo [ghi]perylene are 0.9−2.4 × 10 13 and 10 14 cm −2 for phenanthrene. The measurements indicate fractional abundances of anthracene, pyrene, and 2,3-benzofluorene of a few times 10 −10 . Upper limits in the fractional abundance of benzo [ghi]perylene of a few times 10 −9 and of phenanthrene of few times 10 −8 are inferred. Toward CPD −32 • 1734, we found near 3584 Å an absorption line of OH + , which was discovered in the interstellar medium only very recently. Conclusions. The fractional abundances of PAHs inferred here are up to two orders of magnitude lower than estimated total PAH abundances in the interstellar medium. This indicates that either neutral PAHs are not abundant in translucent molecular clouds or that a PAH population with a wide variety of molecules is present.

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Section: Determination Of Absolute Absorption Cross Sections For Supementioning

confidence: 99%

Section: Laboratory Datamentioning

confidence: 99%

Abundances of PAHs in the ISM: confronting observations with experimental results

Gredel

Carpentier

Rouillé

et al. 2011

A&A

Self Cite

104

View full text Add to dashboard Cite

show abstract

“…Both integrated absorbances are normalized to the amount of deposited neutral PAH, which is determined during the preparation of the ice sample. A quantitative conversion of the PAH molecule into Rouillé et al (2007), f Ehrenfreund et al (1992).…”

Section: Pah:h 2 O Spectroscopymentioning

confidence: 99%

Photochemistry of polycyclic aromatic hydrocarbons in cosmic water ice

Bouwman

Cuppen

Steglich

et al. 2011

A&A

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Context. Mid-infrared emission features originating from polycyclic aromatic hydrocarbons (PAHs) are observed towards photon dominated regions in space. Towards dense clouds, however, these emission features are quenched. Observations of dense clouds show that many simple volatile molecules are frozen out on interstellar grains, forming thin layers of ice. Recently, observations have shown that more complex non-volatile species, presumably including PAHs, also freeze out and contribute to the ongoing solid-state chemistry. Aims. The study presented here aims at obtaining reaction rate data that characterize PAH photochemistry upon vacuum ultraviolet (VUV) irradiation in an interstellar H 2 O ice analogue to explore the potential impact of PAH:H 2 O ice reactions on overall interstellar ice chemistry. To this end, the experimental results are implemented in a chemical model under simple interstellar cloud conditions. Methods. Time-dependent near-UV/VIS spectroscopy on the VUV photochemistry of anthracene, pyrene, benzo[ghi]perylene and coronene containing interstellar H 2 O ice analogs is performed at 25 and 125 K, using an optical absorption setup. Results. Near-UV/VIS absorption spectra are presented for these four PAHs and their photoproducts including cationic species trapped in H 2 O ice. Oscillator strengths of the cation absorption bands are derived relative to the oscillator strength of the neutral parent PAH. The loss of the parent and growth of PAH photoproducts are measured as a function of VUV dose, yielding solid state reaction constants. The rate constants are used in an exploratory astrochemical model, to assess the importance of PAH:H 2 O ice photoprocessing in UV exposed interstellar environments, compared with the timescales in which PAH molecules are incorporated in interstellar ices. Conclusions. All four PAHs studied here are found to be readily ionized upon VUV photolysis when trapped in H 2 O ice and exhibit similar rates for ionization at astronomically relevant temperatures. Depending on the relative efficiency of H 2 O photodesorption and PAH photoionization in H 2 O ice, the latter may trigger a charge induced aromatic solid state chemistry, in which PAH cations play a central role.

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“…https://doi.org/10.1017/S1743921308021960 362 Farid Salama 2005a, b, Rouillé et al 2004Rouillé et al , 2007. Typical spectra are shown in Figures 3 & 4.…”

Section: Pahs In the Visible And Ultraviolet: Pah Ionsmentioning

confidence: 99%

PAHs in Astronomy - A Review

Salama

2008

Proc. IAU

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Abstract. Carbonaceous materials play an important role in space. Polycyclic Aromatic Hydrocarbons (PAHs) are a ubiquitous component of organic matter in space. Their contribution is invoked in a broad spectrum of astronomical observations that range from the ultraviolet to the far-infrared and cover a wide variety of objects and environments from meteorites and interplanetary dust particles to outer Solar System bodies to the interstellar medium in the local Milky Way and in other galaxies. Extensive efforts have been devoted in the past two decades to experimental, theoretical, and observational studies of PAHs. A brief review is given here of the evidence obtained so far for the contribution of PAHs to the phenomena aforementioned. An attempt is made to distinguish the cases where solid evidence is available from cases where reasonable assumptions can be made to the cases where the presence -or the absence -of PAHs is purely speculative at this point.

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S 1 ( A 1 1 ) ← S ( A 1 1 ) transition of benzo[g,h,i]perylene in supersonic jets and rare gas matrices

Cited by 25 publications

References 42 publications

Abundances of PAHs in the ISM: confronting observations with experimental results

Abundances of PAHs in the ISM: confronting observations with experimental results

Photochemistry of polycyclic aromatic hydrocarbons in cosmic water ice

PAHs in Astronomy - A Review

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