D2← D0 transition of the anthracene cation observed by cavity ring-down absorption spectroscopy in a supersonic jet

Sukhorukov, Oleksandr; Staicu, Angela; Diegel, E.; Rouillé, Gaël; Henning, Th.; Huisken, F.

doi:10.1016/j.cplett.2004.01.073

Cited by 60 publications

(38 citation statements)

References 23 publications

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“…e Ar-matrix absorption spectrum from Szczepanski et al (1993b). f Gas-phase absorption spectrum from Sukhorukov et al (2004). g TD-DFT calculation by Weisman et al (2003).…”

Section: Resultsmentioning

confidence: 99%

“…On the contrary, a vast amount of information is available concerning the optical absorption properties of neutral and cationic PAHs in the near-IR, visible, near-UV spectral ranges, most obtained by matrix isolation spectroscopy studies (Salama & Allamandola 1992;Salama et al 1995;Salama 1999;Ruiterkamp et al 2002), but including also some remarkable results in the gas-phase (Romanini et al 1999;Pino et al 1999;Biennier et al 2003Biennier et al , 2004Sukhorukov et al 2004). The astrophysical implications of these data have been discussed in many papers in the literature, specifically with respect to the DIBs issue (Salama et al 1996.…”

Section: Introductionmentioning

confidence: 99%

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Electronic absorption spectra of PAHs up to vacuum UV

Malloci

Mulas

Joblin

2004

A&A

132

131

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Abstract. We computed the absolute photo-absorption cross-sections up to the vacuum ultaviolet (VUV) of a total of 20 Polycyclic Aromatic Hydrocarbons (PAHs) and their respective cations, ranging in size from naphthalene (C 10 H 8 ) to dicoronylene (C 48 H 20 ). We used an implementation in real time and real space of the Time-Dependent Density Functional Theory (TD-DFT), an approach which was proven to yield accurate results for conjugated molecules such as benzene. Concerning the low-lying excited states of π * ← π character occurring in the near-IR, visible and near-UV spectral range, the computed spectra are in good agreement with the available experimental data, predicting vertical excitation energies precise to within a few tenths of eV, and the corresponding oscillator strengths to within experimental errors, which are indeed the typical accuracies currently achievable by TD-DFT. We find that PAH cations, like their parent molecules, display strong π * ← π electronic transitions in the UV, a piece of information which is particularly useful since a limited amount of laboratory data is available concerning the absorption properties of PAH ions in this wavelength range. Moreover, a detailed discussion of the UV-VUV properties of both neutral and cation species is presented. Concerning neutrals, the agreement with existing laboratory data is very good, the specific TD-DFT implementation used in this work apparently being able to reproduce the overall far-UV behaviour, including the broad absorption peak dominated by σ * ← σ transitions, which matches well both in position and width. The implications of these results are discussed in conjunction with the contribution PAH-like molecules are expected to give to the interstellar extinction curve.

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“…e Ar-matrix absorption spectrum from Szczepanski et al (1993b). f Gas-phase absorption spectrum from Sukhorukov et al (2004). g TD-DFT calculation by Weisman et al (2003).…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electronic absorption spectra of PAHs up to vacuum UV

Malloci

Mulas

Joblin

2004

A&A

132

131

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“…Jet-cooled absorption spectra measured in the laboratory (Romanini et al 1999;Biennier et al 2003Biennier et al , 2004Sukhorukov et al 2004;Tan & Salama 2006) were subsequently obtained, and interstellar spectra obtained toward the Perseus molecular cloud complex did reveal weak features that coincide with absorption bands of the naphthalene and anthracene cations (Iglesias-Groth et al 2008. In the case of the anthracene cation, the CRDS spectrum of Sukhorukov et al (2004) reveals an absorption at 7085.7 Å which has an FWHM of 47 Å. While the spectrum of Iglesias-Groth et al (2010) may show an interstellar absorption band near that wavelength, the width of the purported interstellar absorption feature is significantly smaller than 47 Å.…”

Section: The Long and Eventful History Of Dib Candidatesmentioning

confidence: 99%

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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“…Further information on our CRDS setup, giving details of the laser system, the optical components, and the wavelength calibration, can be found elsewhere Sukhorukov et al 2004;Rouillé et al 2007;Carpentier et al 2013).…”

Section: Methodsmentioning

confidence: 99%

Laboratory Studies on the Role of PAHs as DIB Carriers

et al. 2013

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Abstract. The electronic spectroscopy of various polycyclic aromatic hydrocarbon (PAH) molecules has been studied in the laboratory at low temperatures using both molecular beam and matrix isolation spectroscopy techniques. While molecular beam spectra can be readily compared to astronomical observations, the band positions measured in Ne and Ar matrices are extrapolated to obtain rather good estimates for the same transitions in the gas phase. Absolute absorption cross sections are determined for gas-phase and matrix spectra by comparing them with calibrated solution spectra. All laboratory results are analyzed and discussed in view of the role that PAHs can play as carriers of the diffuse interstellar bands (DIBs). Our studies suggest that regular neutral PAHs are not responsible for any of the known strong DIBs.

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D2← D0 transition of the anthracene cation observed by cavity ring-down absorption spectroscopy in a supersonic jet

Cited by 60 publications

References 23 publications

Electronic absorption spectra of PAHs up to vacuum UV

Electronic absorption spectra of PAHs up to vacuum UV

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

Laboratory Studies on the Role of PAHs as DIB Carriers

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