Fluorescence of free pyrene molecules cooled in a supersonic jet

Borisevich, N. A.; Vodovatov, L. B.; D'yachenko, G. G.; Petukhov, V. A.; Semyonov, M. A.

doi:10.1007/bf02606686

Cited by 8 publications

(14 citation statements)

References 11 publications

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“…40 This type of energy level inversion has also been observed in pyrene. 17,31,[41][42][43][44] Consequently, to obtain the correct geometry and vibrational frequencies from either CIS or TDDFT calculations, we need to set the keyword "root = 2" in the input file. However, in comparing our results with those of Gittins et al, 27 we discovered that there were substantial differences between the two calculations in both geometry and frequency.…”

Section: Discussionmentioning

confidence: 99%

Zero kinetic energy photoelectron spectroscopy of jet cooled benzo[a]pyrene from resonantly enhanced multiphoton ionization

Zhang

Harthcock

Han

et al. 2011

The Journal of Chemical Physics

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We report zero kinetic energy (ZEKE) photoelectron spectroscopy of benzo[a]pyrene (BaP) via resonantly enhanced multiphoton ionization (REMPI). Our analysis concentrates on the vibrational modes of the first excited state (S(1)) and those of the ground cationic state (D(0)). Similar to pyrene, another peri-condensed polycyclic aromatic hydrocarbon we have investigated, the first two electronically excited states of BaP exhibit extensive configuration interactions. However, the two electronic states are of the same symmetry, hence vibronic coupling does not introduce any out-of-plane modes in the REMPI spectrum, and Franck-Condon analysis is qualitatively satisfactory. The ZEKE spectra from the in-plane modes observed in the REMPI spectrum demonstrate strong propensity in preserving the vibrational excitation of the intermediate state. Although several additional bands in combination with the vibrational mode of the intermediate state are identifiable, they are much lower in intensity. This observation implies that the molecular structure of BaP has a tremendous capability to accommodate changes in charge density. All observed bands of the cation are IR active, establishing the role of ZEKE spectroscopy in mapping out far infrared bands for astrophysical applications.

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Section: Discussionmentioning

confidence: 99%

Zero kinetic energy photoelectron spectroscopy of jet cooled benzo[a]pyrene from resonantly enhanced multiphoton ionization

Zhang

Harthcock

Han

et al. 2011

The Journal of Chemical Physics

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“…Although these bands are supposed to be b-type, it is impossible to assign each observed band explicitly. The vibrational analysis in the S 0 and S 1 states were previously reported by Borisevich et al 11,12 based on the results of semiempirical MO/8 model calculation. We resolved the partially overlapped bands in the fluorescence excitation spectrum at the higher resolution.…”

Section: -3mentioning

confidence: 98%

“…We could clearly resolve and identify even weak vibronic bands al- though the spectral features were almost identical to those reported before. [9][10][11][12][13] The excess energies of observed vibronic bands of pyrene-h 10 and pyrene-d 10 are listed in Tables I and II, respectively. In order to make reliable vibrational assignments, we observed the rotational envelopes of individual vibronic bands.…”

Section: ͑1͒mentioning

confidence: 99%

“…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%

“…This situation is similar to that of naphthalene and the S 1 state is designated by 1 L b . 14 Relatively strong b 1g vibronic bands could be seen in the fluorescence excitation spectrum, [9][10][11][12][13] providing evidence of strong vibronic coupling between the S 1 1 B 3u and S 2 1 B 2u states. The S 1 ↔ S 0 transition moment is small so that the radiative lifetime of the S 1 state is very long.…”

Section: Introductionmentioning

confidence: 99%

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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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