17,020 research outputs found
Optical spectra of push-pull chromophores in solution: a simple model
No full textWe extend the self-consistent two-state model, already proposed to describe linear and nonlinear spectral properties of push−pull chromophores in solution, to describe vibrational spectra and to account for inhomogeneous broadening effects occurring in polar solvents. The model, not relying on perturbative expansions of the solute−solvent interaction, offers a simple and internally consistent description of electronic and vibrational spectra. Exotic and apparently unrelated phenomena, like the narrowing of time-resolved emission bands and the dispersion of resonant Raman frequencies with the excitation line find a natural explanation in the proposed approach
Push-pull chromophores: NLO responses, solvatochromism and vibrational spectra in a simple non-perturbative model
No full textThe diverse and fascinating properties of push–pull chromophores demonstrate their intrinsic non-linearity, and suggest that standard perturbative approaches are inadequate to describe their behavior. NLO responses of push–pull chromophores are strongly affected by the surrounding and large environmental effects are observed in absorption and emission spectra. Vibrational spectra show impressive dependence on the embedding medium, with unusual inhomogeneous broadening effects appearing in polar solvents. All these seemingly unrelated phenomena are naturally understood based on a simple two-state model self-consistently accounting for the coupling of electrons to molecular vibrations and to the surrounding medium. The few model parameters are extracted from experiment, leading to a simple yet accurate description of the exotic properties of push–pull chromophores
A non-perturbative approach to solvatochromic shifts of push-pull chromophores
No full textThe two-state model for push–pull chromophores (the DA dimer model) is extended to account for the coupling of electrons to molecular vibrations and for the interaction with the solvent. The resulting self-consistent two-state model is solved exactly. In this Letter, we present exact results on linear absorption and emission spectra. Standard perturbative treatments of both vibronic and solvent effects on spectral properties are proved to fail in highly non-linear systems as push–pull chromophores. The use of solvatochromic data to extract mesomeric dipole moments as well as to investigate the dynamics of the solvent relaxation is critically reviewed
On the ab initio evaluation of Hubbard parameters. II. The k-(BEDT-TTF) Cu[N(CN) ]Br crystal.
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