The <i>S</i>1(<i>n</i>, π*) states of acetaldehyde and acetone in supersonic nozzle beam: Methyl internal rotation and C=O out-of-plane wagging

Baba, Masaaki; Hanazaki, Ichiro; Nagashima, Umpei

doi:10.1063/1.448886

Cited by 134 publications

(67 citation statements)

References 36 publications

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“…16 This dipole-forbidden transition has been the subject of many experimental studies [17][18][19][20] concentrating on aspects such as the role of vibronic coupling and interaction with triplet states. 16,21,22 The first Rydberg state derives from excitation of a lone pair electron to the 3s Rydberg orbital, giving rise to the 1 1 B 2 state located at 6.35 eV. 14,[23][24][25][26] Vibronic coupling comes prominently forward in the excitation spectra of this state by the activity of the 12 (a 2 ) and 24 (b 1 ) nontotally-symmetric vibrations.…”

Section: Introductionmentioning

confidence: 99%

Vibronic coupling in excited states of acetone

Steege

Wirtz

2002

The Journal of Chemical Physics

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Photoelectron spectroscopy of Rydberg states of acetone-h 6 and -d 6 populated by two-or three-photon excitation has been employed to unravel the vibronic description of excited-state levels. For the 3p Rydberg states vibronic transitions have been reanalyzed, leading to various reassignments and the observation of hitherto nonreported transitions. In addition, several ionic vibrational frequencies could be determined. At higher excitation energies previously identified, and in the present study newly identified, members of two Rydberg series have been characterized. The ns Rydberg series was explored up to the 8s state, the nd series up to the 7d state. Based upon the unambiguous assignments of vibronic character that we obtain for excited-state levels, various valence-Rydberg and Rydberg-Rydberg vibronic coupling pathways come to light and are analyzed.

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Section: Introductionmentioning

confidence: 99%

Vibronic coupling in excited states of acetone

Steege

Wirtz

2002

The Journal of Chemical Physics

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“…The absorption spectrum of the acetone molecule, C 3 H 6 O, in the near ultraviolet has been studied for long [32,[54][55][56][57][58]. The first singlet electronic transition A 2 ← A 1 corresponds to an excitation n → π , the same type of transition studied for the formaldehyde, H 2 CO, discussed in the last section.…”

Section: B Formaldehyde H 2 Comentioning

confidence: 99%

Theoretical investigations on valence vibronic transitions

Borges¹,

Rocha²,

Bielschowsky³

2005

Braz. J. Phys.

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This article reviews previously employed methods to study several valence electronic transitions, optically forbidden or not, enhancing intensity through vibronic coupling. Electronic transition dipole moments were calculated using several ab initio methods including electron correlation. In this method the square of the electronic transition dipole moments are directly calculated along the normal coordinates of vibration and then expanded with a polynomial function. Afterwards, analytical vibrational integration using harmonic wave functions, of the square of the transition moments function, allows us to obtain partial (i.e. for each vibrational mode) and total optical oscillator strengths (OOS), for the vibronic transition of interest. We illustrate the accuracy of the method through valence transitions of benzene (C 6 H 6 ), formaldehyde (H 2 CO), acetone (C 3 H 6 O) and formic acid (HCOOH).

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“…29 The structure has been attributed to progressions in Franck-Condon active vibrational modes of the S1 ← S0 excitation, most probably combination bands of the CO stretch ν4, CH3 rock ν14, and CH3 torsion ν15 modes. 56,57 The expected yield of CH3 and HCO, IIa ( ), can be calculated as the product of the absorption cross section and the photolysis quantum yield for channel IIa, both functions of the excitation wavelength:…”

Section: Phofex Spectroscopymentioning

confidence: 99%

Photodissociation dynamics of acetone studied by time-resolved ion imaging and photofragment excitation spectroscopy

Toulson

Fishman

Murray

2018

Phys. Chem. Chem. Phys.

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Time-resolved ion imaging measurements have been performed to explore the photochemistry of acetaldehyde at photolysis wavelengths spanning the range 265-328 nm. Ion images recorded probing CH3 radicals with single-photon VUV ionization show different dissociation dynamics in three distinct wavelength regions. At the longest photolysis wavelengths, λ > 318 nm, CH3 radicals are formed over tens of nanoseconds with a speed distribution that is consistent with statistical unimolecular dissociation on the S0 surface following internal conversion. In the range 292 nm ≤ λ ≤ 318 nm, dissociation occurs almost exclusively on the T1 surface following intersystem crossing and passage over a barrier, leading to the available energy being partitioned primarily into photofragment recoil. The CH3 speed distributions become bimodal at λ < 292 nm, in addition to the translationally fast T1 products a new translationally slow, but non-statistical, component appears and grows in importance as the photolysis wavelength is decreased. Photofragment excitation (PHOFEX) spectra of CH3CHO obtained probing CH3 and HCO products are identical across the absorption band, indicating that three-body fragmentation is not responsible for the non-statistical slow component. Rather, translationally slow products are attributed to dissociation on S0, accessed via a conical intersection between the S1 and S0 surfaces at extended C-C distances. Time-resolved ion images of CH3 radicals measured using a picosecond laser operating at a photolysis wavelength of 266 nm show that product formation on T1 and S0 via the conical intersection occurs with time constants of 240 and 560 ps, respectively.3

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The S1(n, π*) states of acetaldehyde and acetone in supersonic nozzle beam: Methyl internal rotation and C=O out-of-plane wagging

Cited by 134 publications

References 36 publications

Vibronic coupling in excited states of acetone

Vibronic coupling in excited states of acetone

Theoretical investigations on valence vibronic transitions

Photodissociation dynamics of acetone studied by time-resolved ion imaging and photofragment excitation spectroscopy

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