Ultraviolet spectroscopy of pyrene in a supersonic jet and in liquid helium droplets

Rouillé, Gaël; Krasnokutski, Serge A.; Huisken, F.; Henning, Thomas; Sukhorukov, Oleksandr; Staicu, Angela

doi:10.1063/1.1651476

Cited by 38 publications

(28 citation statements)

References 39 publications

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“…We propose that the structure is caused by an interaction between the S 2 state and the vibrational manifold of the S 1 state. Studies in molecular beams have shown that this interaction takes place in Pyr (see Rouillé et al 2004 and references therein). The resulting vibronic structure in the S 2 ← S 0 transition is not noticeable in matrix-isolated spectra of Pyr because the matrix-induced band broadening makes the bands overlap.…”

Section: Pyrene and Its Derivativesmentioning

confidence: 99%

On the Relevance of Polyynyl-Substituted Polycyclic Aromatic Hydrocarbons to Astrophysics

Rouillé

Steglich

Carpentier

et al. 2012

ApJ

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We report on the absorption spectra of the polycyclic aromatic hydrocarbon (PAH) molecules anthracene, phenanthrene, and pyrene carrying either an ethynyl (−C 2 H) or a butadiynyl (−C 4 H) group. Measurements were carried out in the mid infrared at room temperature on grains embedded in CsI pellets and in the near ultraviolet at cryogenic temperature on molecules isolated in Ne matrices. The infrared measurements show that interstellar populations of polyynyl-substituted PAHs would give rise to collective features in the same way non-substituted PAHs give rise to the aromatic infrared bands. The main features characteristic of the substituted molecules correspond to the acetylenic CH stretching mode near 3.05 µm and to the almost isoenergetic acetylenic CCH in-and out-of-plane bending modes near 15.9 µm. Sub-populations defined by the length of the polyynyl side group cause collective features which correspond to the various acetylenic CC stretching modes. The ultraviolet spectra reveal that the addition of an ethynyl group to a non-substituted PAH molecule results in all its electronic transitions being redshifted. Due to fast internal energy conversion, the bands at shorter wavelengths are significantly broadened. Those at longer wavelengths are only barely affected in this respect. As a consequence, their relative peak absorption increases. The substitution with the longer butadiynyl chain causes the same effects with a larger magnitude, resulting in the spectra to show a prominent if not dominating π-π * transition at long wavelength. After discussing the relevance of polyynyl-substituted PAHs to astrophysics, we conclude that this class of highly conjugated, unsaturated molecules are valid candidates for the carriers of the diffuse interstellar bands.

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Section: Pyrene and Its Derivativesmentioning

confidence: 99%

On the Relevance of Polyynyl-Substituted Polycyclic Aromatic Hydrocarbons to Astrophysics

Rouillé

Steglich

Carpentier

et al. 2012

ApJ

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“…[11][12][13] Only a limited number of PAHs have been studied by CRDS due to the difficulty of bringing these low-vapor pressure molecules into the gas phase in amounts detectable under the laboratory conditions that are relevant for astrophysical studies. [14][15][16][17][18] We select the S 1 ͑ 1 B 3u ͒ ← S 0 ͑ 1 A g ͒ transition of neutral perylene because it can be served as a model system for the study of middle-size compact PAHs of similar structure. The absorption spectra of both neutral and ionized perylene have been measured with MIS.…”

Section: Introductionmentioning

confidence: 99%

Cavity ring-down spectroscopy and theoretical calculations of the S1(B3u1)←S(Ag1) transition of jet-cooled perylene

Tan

Salama

2005

The Journal of Chemical Physics

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As part of our long-term program to test the diffuse interstellar band-polycyclic aromatic hydrocarbon hypothesis, we have investigated the S(1)<--S(0) electronic transition of neutral perylene (C(20)H(12)) in a combined experimental and theoretical study. Jet-cooled perylene was prepared with a pulsed discharge slit nozzle and detected by cavity ring-down spectroscopy. A number of vibronic features were observed in the 24 000-24 900 cm(-1) spectral range. Density functional and ab initio calculations were performed to determine the geometries, harmonic vibrational frequencies, and normal coordinates of both the S(0) and S(1) electronic states. A rotational temperature of 52+/-5 K was derived from a rotational contour analysis of the vibronic band associated with the 0-0 transition. A Franck-Condon treatment was carried out to calculate the vibronic spectrum of the S(1)<--S(0) transition. A good agreement was found between the calculated and the experimental spectra. A vibrational assignment is proposed and six normal modes are identified. The contribution of neutral compact polycyclic aromatic hydrocarbons to the diffuse interstellar bands is briefly discussed.

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“…1-7 Ever since emission of pyrene was observed from the comet P/Halley, 8 the gaseous molecule has attracted the interest of many researchers, and several studies of the jetcooled pyrene molecule have been reported. [9][10][11][12][13] Its vibrational and rotational structures, however, have not been satisfactorily analyzed yet, and more careful measurements of jet spectroscopy and ultrahigh-resolution spectroscopy are desired to accurately determine the energy level structure of the isolated pyrene molecule. Pyrene possesses 16 electrons and is not subject to Hückel's 4n + 2 rule, which states that cyclic planar molecules in which each atom has a p orbital are aromatic if they contain 4n +2 electrons.…”

Section: Introductionmentioning

confidence: 99%

Vibrational and rotational structure and excited-state dynamics of pyrene

Baba

Saitoh

Kowaka

et al. 2009

The Journal of Chemical Physics

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Vibrational level structure in the S(0) (1)A(g) and S(1) (1)B(3u) states of pyrene was investigated through analysis of fluorescence excitation spectra and dispersed fluorescence spectra for single vibronic level excitation in a supersonic jet and through referring to the results of ab initio theoretical calculation. The vibrational energies are very similar in the both states. We found broad spectral feature in the dispersed fluorescence spectrum for single vibronic level excitation with an excess energy of 730 cm(-1). This indicates that intramolecular vibrational redistribution efficiently occurs at small amounts of excess energy in the S(1) (1)B(3u) state of pyrene. We have also observed a rotationally resolved ultrahigh-resolution spectrum of the 0(0) (0) band. Rotational constants have been determined and it has been shown that the pyrene molecule is planar in both the S(0) and S(1) states, and that its geometrical structure does not change significantly upon electronic excitation. Broadening of rotational lines with the magnetic field by the Zeeman splitting of M(J) levels was very small, indicating that intersystem crossing to the triplet state is minimal. The long fluorescence lifetime indicates that internal conversion to the S(0) state is also slow. We conclude that the similarity of pyrene's molecular structure and potential energy curve in its S(0) and S(1) states is the main cause of the slow radiationless transitions.

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Ultraviolet spectroscopy of pyrene in a supersonic jet and in liquid helium droplets

Cited by 38 publications

References 39 publications

On the Relevance of Polyynyl-Substituted Polycyclic Aromatic Hydrocarbons to Astrophysics

On the Relevance of Polyynyl-Substituted Polycyclic Aromatic Hydrocarbons to Astrophysics

Cavity ring-down spectroscopy and theoretical calculations of the S1(B3u1)←S(Ag1) transition of jet-cooled perylene

Vibrational and rotational structure and excited-state dynamics of pyrene

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