Torsional potential energy surfaces and vibrational levels in trans Stilbene

Orlandi, Giorgio; Gagliardi, Laura; Melandri, Sonia; Camináti, Walther

doi:10.1016/s0022-2860(02)00147-3

Cited by 22 publications

(33 citation statements)

References 32 publications

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“…[69][70][71] To be able to simulate the Franck-Condon spectra, we set the corresponding frequencies to be real-valued, small positive numbers taken from experiment ͑compare Table II͒ as will be outlined in detail below. Imaginary frequencies were obtained from both the TDDFT and the CASSCF treatment of the S 1 state for mode 37 ͑A u ͒ representing the ethylenic torsion.…”

Section: B High-resolution S 0 \ S 1 Absorption and S 0 ] S 1 Fluorementioning

confidence: 99%

“…Based on both experiment 56 and theory 69 it has been emphasized that the pronounced anharmonicity of this torsional potential is indispensable for understanding the vibrational level spacing and the intensities of the Franck-Condon progressions of mode 37. 4͑a͔͒, indeed, exhibits pronounced features at 83 cm −1 and a weaker line at 95 cm −1 even though the calculated intensities of both lines are still somewhat too low as compared to the experimental results.…”

Section: ͑42͒mentioning

confidence: 99%

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Ab initio spectroscopy and photoinduced cooling of the trans-stilbene molecule

Tatchen

Pollak

2008

The Journal of Chemical Physics

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We present a theoretical study of the S(0)-->S(1) and S(0)<--S(1) vibronic spectra for trans-stilbene. Franck-Condon spectra in the harmonic approximation are generated for the complete system with 72 degrees of freedom by means of an analytic time-dependent approach accounting for Dushinsky rotations and thermal effects. The force fields are computed by means of density functional theory (DFT) and time-dependent DFT, on the one hand, and ab initio complete active space self-consistent field theory, on the other hand. The B3LYP functional shows that almost planar potential energy surface minima are found for the S(0) and S(1) state. Imposing C(2h) symmetry constraints, we obtain low-temperature high-resolution Franck-Condon spectra for both absorption and emission which are in reasonably good agreement with the experimental spectra measured by Syage et al. [J. Chem. Phys. 81, 4685 (1984)] in supersonic jets. Due to thermal population of low-energy modes, the room temperature absorption spectrum is very broad. An almost structureless band which extends over several thousand cm(-1) is obtained from the present theory and agrees with the experimental absorption band shape. Finally, within the harmonic model, we study the effect of photoexcitation on the energy distribution in the excited S(1) state. We find noticeable cooling of approximately 20 K within a frequency interval spanning from -400 to 200 cm(-1) around the 0-0 transition. This indicates that photoinduced cooling must be taken into account when considering the dynamics of the photoinduced isomerization of trans-stilbene. Moreover, this is not the final word, as anharmonicity of the low frequency modes must be taken into account to obtain a full picture which would explain both the energy dependence of the isomerization rates as well as the dependence on the pressure of an external buffer gas.

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Section: B High-resolution S 0 \ S 1 Absorption and S 0 ] S 1 Fluorementioning

confidence: 99%

Section: ͑42͒mentioning

confidence: 99%

Ab initio spectroscopy and photoinduced cooling of the trans-stilbene molecule

Tatchen

Pollak

2008

The Journal of Chemical Physics

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“…In addition, our gasphase calculations for an isolated DEST cation (Supplementary Figure S13) estimate a barrier of 0.052 eV for the rotation of the acceptor moiety as it moves out of the molecular plane for TICT-state formation. Using a simple Arrhenius model with an approximated low-frequency torsional mode of ∼50−60 cm −1 (C−C bond rotation) 42,43 for the pre-exponential factor, we obtained a rate of ∼2 × 10 11 s −1 for excited relaxation to the TICT minimum. The calculated rate suggests a rise time of ∼1−5 ps, which is slightly longer than the experimentally observed rise times in methanol or water by TA.…”

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confidence: 99%

Transient Raman Snapshots of the Twisted Intramolecular Charge Transfer State in a Stilbazolium Dye

Karmakar

Ambastha

Jha

et al. 2020

J. Phys. Chem. Lett.

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Optically triggered twisted intramolecular charge transfer (TICT) states in donor–acceptor chromophores form the molecular basis for designing bioimaging probes that sense polarity, microviscosity, and pH in vivo. However, a lack of predictive understanding of the “twist” localization precludes a rational design of TICT-based dyes. Here, using femtosecond stimulated Raman spectroscopy, we reveal a distinct Raman signature of the TICT state for a stilbazolium-class mitochondrial staining dye. Resonance-selective probing of 4-N,N-diethylamino-4″-N′-methyl-stilbazolium tosylate (DEST) tracks the excited-state structure of the dye as it relaxes to a TICT state on a picosecond time scale. The appearance of a remarkably blue-shifted C=C stretching mode at 1650 cm–1 in the TICT state is attributed to the “twist” of a single bond adjacent to the ethylenic π-bridge in the DEST backbone based on detailed electronic structure calculations and vibrational mode analysis. Our work demonstrates that the π-bridge, connecting the donor and acceptor moieties, influences the spatial location of the “twist” and offers a new perspective for designing organelle-specific probes through cogent tuning of backbone dynamics.

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“…Since the large dimensions of the systems prevent the use of the most sophisticated post-Hartree-Fock models, several semi-empirical or perturbative methods were used in conjunction with approaches rooted into the density functional theory (DFT) to get an adequate picture of conjugation length effects in these systems. 12 DFT and timedependent (TD)-DFT at the B3LYP/6-31G(d) and 6-311++G(d,p) levels of theory were employed to determine the Raman, infrared (IR) and fluorescence excitation spectra in the S1 state 13 with the help of empirical scaling factors. For instance, computations at the configuration interaction (CI) level indicated that TSB adopts a cis conformation in the excited state 7 , whereas the molecule could be non-planar in its ground electronic state.…”

Section: Introductionmentioning

confidence: 99%

New insights into the vibrational and optical signatures of trans-stilbene via integrated experimental and quantum mechanical approaches

Massuyeau

Faulques

Latouche

et al. 2016

Phys. Chem. Chem. Phys.

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The structure, spectroscopic parameters and optical properties of stilbene have been investigated by a computational protocol including suitable treatment of anharmonic contributions together with new experimental results. A full reproduction of the 500-3500 cm(-1) IR spectrum has been possible using the VPT2 approach and new insights are provided in the 6000 cm(-1) region where typical signatures have been characterized as a set of overtones and combination bands. Vibrational contributions to electronic transitions have been taken into account to simulate the optical (absorption and emission) properties of stilbene. Spectra simulated by employing the state-of-the-art Adiabatic Hessian model coupled to global hybrid functionals are in remarkable agreement with their experimental counterparts and the inclusion of Herzberg-Teller contributions further improves the results with respect to those delivered by the basic Franck-Condon model.

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Torsional potential energy surfaces and vibrational levels in trans Stilbene

Cited by 22 publications

References 32 publications

Ab initio spectroscopy and photoinduced cooling of the trans-stilbene molecule

Ab initio spectroscopy and photoinduced cooling of the trans-stilbene molecule

Transient Raman Snapshots of the Twisted Intramolecular Charge Transfer State in a Stilbazolium Dye

New insights into the vibrational and optical signatures of trans-stilbene via integrated experimental and quantum mechanical approaches

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