The effect of syn–anti isomerism on the lowest valence transitions of 1,1′-bicyclohexylidene. An ab initio MRDCI investigation

Havenith, Remco W. A.; Jenneskens, Leonardus W.; Lenthe, Joop H. van

doi:10.1016/s0009-2614(97)01183-4

Cited by 9 publications

(8 citation statements)

References 15 publications

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“…Surprisingly, it was found that this low-lying valence transition only occurs for the anti -conformer of BCH; ,, for the syn -conformer, which is present in nearly identical amounts in solution and gas phase, a differently polarized π → σ* valence transition was calculated, being ca. 1 eV higher in excitation energy . The fact that the calculated oscillator strength for the π → σ* valence transition in the anti -conformer is significantly lower than that calculated for the (π,π*) valence state, whereas the solution and gas-phase experimentsin which in this scenario the anti -conformer is the only one contributing to the higher energy band, while both conformers contribute to the lower oneindicates that both transitions have similar oscillator strengths, and the rather large difference between observed and calculated energy gaps remained, however, points of concern.…”

Section: Introductionmentioning

confidence: 82%

Isolated Building Blocks of Photonic Materials: High-Resolution Excited-State Photoelectron Spectroscopy of Jet-Cooled Tetramethylethylene and 1,1‘-Bicyclohexylidene

Rijkenberg¹,

Buma²,

Walree³

et al. 2002

J. Phys. Chem. A

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The spectroscopy and photophysics of tetramethylethylene and 1,1‘-bicyclohexylidene have been investigated using excited-state photoelectron spectroscopy in combination with multiphoton excitation. Vibronic coupling within the full manifold of the excited singlet states has been shown to play a dominant role in determining the spectroscopic properties of these compounds. Although this vibronic coupling inhibits the determination of excited state excitation energies by excitation spectroscopy, it enables at the same time their observation in the photoelectron spectra. As a result, a large number of previously unobserved Rydberg states could be located and assigned. For both molecules ionization from the Rydberg states is observed to be heavily perturbed by ionization from the underlying quasi-continuum of the (π,π*) valence state. The photoelectron spectra of 1,1‘-bicyclohexylidene reveal that the state around 55000 cm-1 (6.82 eV), which has previously been assigned as a second valence state, does not show the ionization pattern expected on the basis of previous suggestions made for the character of this state. On the basis of this observation, configuration mixing between the (π,π*) valence state and the (π,3d) Rydberg manifold is offered as a possible explanation.

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Section: Introductionmentioning

confidence: 82%

Isolated Building Blocks of Photonic Materials: High-Resolution Excited-State Photoelectron Spectroscopy of Jet-Cooled Tetramethylethylene and 1,1‘-Bicyclohexylidene

Rijkenberg¹,

Buma²,

Walree³

et al. 2002

J. Phys. Chem. A

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“…In the present Communication we report the results of an ab initio study on the excited singlet states of the anti ‐conformer of BCH and their electronic properties 22. With the Rydberg–valence mixing discussed above for ethene in mind, we have investigated the amount of configuration mixing between the ππ* valence state and the Rydberg manifold as a function of the diffuseness of the basis set employed and the effect of this mixing on the electronic properties of the excited states.…”

Section: Cis Calculated Vertical Excitation Energies [Ev] and Oscillamentioning

confidence: 99%

Rydberg–Valence Interactions in Monoolefins: Dispersing Electronic Properties in 1,1′‐Bicyclohexylidene

et al. 2002

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Disentangling the embrace: Calculations on the electronic structure of 1,1′‐bicyclohexylidene (shown in the graphic) indicate that electronic coupling of the excited ππ* valence state with Rydberg states lies at the basis of the hitherto poorly understood presence of two low‐lying electronic states with valencelike properties. States with similar characteristics are predicted for the entire class of monoolefins.

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“…MRD-CI/6-31G* (multireference configuration interaction) calculations on anti-BCH [20] predicted two transitions polarized along the C=C double bond at 9.28 (calculated f = 0.84) and 10.49 eV (f = 0.13) with valence pp* and ps* character, respectively. The low-quality basis set employed in this early work is purposely not flexible enough to describe Rydberg states, and although further CI and perturbation theory calculations [21][22][23] with the same basis set agreed with this assignment, the reliability of such results is not guaranteed.…”

Section: Introductionmentioning

confidence: 91%

Rydberg or Valence? The Long‐Standing Question in the UV Absorption Spectrum of 1,1′‐Bicyclohexylidene

2008

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The electronic excited states of the olefin 1,1'-bicylohexylidene (BCH) are investigated using multiconfigurational complete active space self-consistent-field second order perturbation theory in its multi-state version (MS-CASPT2). Our calculations undoubtedly show that the bulk of the intensity of the two unusually intense bands of the UV absorption of BCH measured with maxima at 5.95 eV and 6.82 eV in the vapor phase are due to a single pi pi* valence excitation. Sharp peaks reported in the vicinity of the low-energy feature in the gas phase correspond to the beginning of the pi 3s(R) Rydberg series. By locating the origin of the pi pi* band at 5.63 eV, the intensity and broadening of the observed bands and their presence in solid phase is explained as the vibrational structure of the valence pi pi* transition, which underlies the Rydberg manifold as a quasi-continuum.

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The effect of syn–anti isomerism on the lowest valence transitions of 1,1′-bicyclohexylidene. An ab initio MRDCI investigation

Cited by 9 publications

References 15 publications

Isolated Building Blocks of Photonic Materials: High-Resolution Excited-State Photoelectron Spectroscopy of Jet-Cooled Tetramethylethylene and 1,1‘-Bicyclohexylidene

Isolated Building Blocks of Photonic Materials: High-Resolution Excited-State Photoelectron Spectroscopy of Jet-Cooled Tetramethylethylene and 1,1‘-Bicyclohexylidene

Rydberg–Valence Interactions in Monoolefins: Dispersing Electronic Properties in 1,1′‐Bicyclohexylidene

Rydberg or Valence? The Long‐Standing Question in the UV Absorption Spectrum of 1,1′‐Bicyclohexylidene

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