Substituent Effects in Molecular Electronic Relaxation Dynamics via Time-Resolved Photoelectron Spectroscopy:  ππ* States in Benzenes

Lee, Shih‐Huang; Tang, Kuo‐Chun; Chen, I‐Chia; Schmitt, Michael; Shaffer, James P.; Schultz, Thomas; Underwood, Jonathan G.; Zgierski, Marek Z.; Stolow, Albert

doi:10.1021/jp021096h

Cited by 64 publications

(86 citation statements)

References 84 publications

(189 reference statements)

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“…This assumption, together with the electronic correlations described above and summarized in table 2, allows approximate photoelectron band energies to be predicted between excited states, and thus the TRPES bands can be assigned to first order, as illustrated in figure 1. Such an approximate assignment method has been reported in the literature as an analysis tool for time-resolved photoionisation studies of styrene and other molecules 18,24,29 and provides theoretical band energies that agree well with those observed.…”

Section: Theorymentioning

confidence: 56%

Ultrafast dynamics through conical intersections and intramolecular vibrational energy redistribution in styrene

Nunn

Minns

Spesyvtsev

et al. 2010

Phys. Chem. Chem. Phys.

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We report a femtosecond time-resolved photoelectron spectroscopy (TRPES) investigation of internal conversion in the first two excited singlet electronic states of styrene. We find that radiationless decay through an S 1 /S 0 conical intersection occurs on a timescale of ~4 ps following direct excitation to S 1 with 0.6 eV excess energy, but that the same process is significantly slower (~20 ps) if it follows internal conversion from S 2 to S 1 after excitation to S 2 with 0.3 eV excess energy (0.9 eV excess energy in S 1 ).

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Section: Theorymentioning

confidence: 56%

Ultrafast dynamics through conical intersections and intramolecular vibrational energy redistribution in styrene

Nunn

Minns

Spesyvtsev

et al. 2010

Phys. Chem. Chem. Phys.

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“…6 shows indeed a very small peak around 1.4 eV. If this peak is real-but the present experimental conditions do not allow us to make a decision on this-then the 1.160 and 1.182 eV peaks can be readily ͑re͒assigned as the 5 ϩ ϭ1 and 4 ϩ ϭ1 peaks. For maleimide, the photoelectron spectrum via S 4 showed two ionization routes.…”

Section: Multiphoton Ionization and Excited-state Photoelectron Spectmentioning

confidence: 78%

“…Importantly, Table V reveals that ionization of S 3 is associated with a fundamentally different Franck-Condon behavior. Here, a large activity of 8 ϩ and a smaller activity of 7 ϩ is predicted, but now the activity of 4 ϩ has disappeared and has been replaced by an activity of 5 ϩ that is as large as that of 8 ϩ . For maleimide it has been shown that the triplet quantum yield is close to unity.…”

Section: Multiphoton Ionization and Excited-state Photoelectron Spectmentioning

confidence: 90%

“…A recent study of Stolow et al gives in this respect a good overview of what has been done up till now. 5 A useful concept that was introduced in the studies of Stolow et al was that of corresponding 4 and complementary 3 ionization correlations, i.e., the ionization behavior of coupled states that correlate with the same and with different ionic states, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Spectroscopy and dynamics of excited states in maleimide and N-methyl maleimide: Ionic projection and ab initio calculations

Steege

Buma

2003

The Journal of Chemical Physics

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The state that is responsible for the strong one-photon absorption around 200 nm in the vapor absorption spectrum of maleimide and N-methyl maleimide has been investigated using excited-state photoelectron spectroscopy in combination with ab initio calculations. The projection of the wave function of the excited state on the ionic manifold done in this way reveals multiple, vibrationally resolved, ionization pathways to ground- and excited states of the radical cation, which provide direct evidence for electronic couplings with other, lower-lying states. From a comparison of the experimental intensity distribution over the ionic vibrational states with ab initio calculated Franck–Condon factors, we are able to elucidate the role of the various electronically excited states in the ionization process. The experiments also provide the first determination of adiabatic ionization energies in the two molecules. For maleimide values of 10.330 and 10.903 eV are found for D0 and D1, respectively; for N-methyl maleimide D0 is found at 9.897 or, in an alternative interpretation of the spectrum, at 9.676 eV. Calculations and experiment demonstrate that in this molecule the ground ionic state changes its character with respect to maleimide from a lone pair to a π orbital ionization.

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“…4,5 This particular feature of benzaldehyde has been exploited by numerous studies attempting an explanation of its photophysics. Experiments to this end have been performed on benzaldehyde in the vapor, [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] in solution, 21 and in matrices. [22][23][24] The proximity and nature of low-lying n * and * states of both singlet and triplet manifolds have been a main focus both experimentally and theoretically.…”

Section: A Benzaldehydementioning

confidence: 99%

Ultrafast electron diffraction: Excited state structures and chemistries of aromatic carbonyls

Park

Feenstra

Zewail

2006

The Journal of Chemical Physics

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The photophysics and photochemistry of molecules with complex electronic structures, such as aromatic carbonyls, involve dark structures of radiationless processes. With ultrafast electron diffraction ͑UED͒ of isolated molecular beams it is possible to determine these transient structures, and in this contribution we examine the nature of structural dynamics in two systems, benzaldehyde and acetophenone. Both molecules are seen to undergo a bifurcation upon excitation ͑S 2 ͒. Following femtosecond conversion to S 1 , the bifurcation leads to the formation of molecular dissociation products, benzene and carbon monoxide for benzaldehyde, and benzoyl and methyl radicals for acetophenone, as well as intersystem crossing to the triplet state in both cases. The structure of the triplet state was determined to be "quinoidlike" of * character with the excitation being localized in the phenyl ring. For the chemical channels, the product structures were also determined. The difference in photochemistry between the two species is discussed with respect to the change in large amplitude motion caused by the added methyl group in acetophenone. This discussion is also expanded to compare these results with the prototypical aliphatic carbonyl compounds, acetaldehyde and acetone. From these studies of structural dynamics, experimental and theoretical, we provide a landscape picture for, and the structures involved in, the radiationless pathways which determine the fate of molecules following excitation. For completeness, the UED methodology and the theoretical framework for structure determination are described in this full account of an earlier communication ͓J. S. Feenstra et al., J. Chem. Phys. 123, 221104 ͑2005͔͒.

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Substituent Effects in Molecular Electronic Relaxation Dynamics via Time-Resolved Photoelectron Spectroscopy: ππ* States in Benzenes

Cited by 64 publications

References 84 publications

Ultrafast dynamics through conical intersections and intramolecular vibrational energy redistribution in styrene

Ultrafast dynamics through conical intersections and intramolecular vibrational energy redistribution in styrene

Spectroscopy and dynamics of excited states in maleimide and N-methyl maleimide: Ionic projection and ab initio calculations

Ultrafast electron diffraction: Excited state structures and chemistries of aromatic carbonyls

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