TPA spectra

B3LYP geometries, obtained as a result of density functional theory (DFT) calculations, were found to underestimate calculated transition energies compared to experiment in both OPA and TPA spectra (see Fig. 3.3) [236]. 

Figure 3.22. TPA spectra of anthracene in crystal (o b) and solution ( ) more details can be found in Ref. [5]. (From Ref. [5] with permission of the American Institute of...

TPA spectra were also measured for the bis-dioxaborines 91 and 92 by TPEF (Table 3.8). The dioxaborine unit exhibits an electron-withdrawing unit. The main TPA of 91 and 92 occurs into a higher excited state. This is consistent with the findings for other centra symmetric systems. A minor peak was observed at longer wavelength in the TPA spectrum of 91, whose excitation energy is located near the OPE state. 

In good agreement with the model described in Fig. 2b for push-pull molecules, TPA spectra match one-photon absorption curves this confirms that the value of cttpa is dominated by the dipolar term of Eq. 5 and that dipolar molecules efficient in quadratic NLO processes (see Eq. 6) should present high TPA responses. This trend has been illustrated by work on azo-aromatic... 

Fig. 13. A portion of the single photon absorption and TPA spectra of Cs2U02Cl4 at 4.2 K. Energy scales for the two experiments are matched in paired segments from Ref. [40]...

Itvo-Plioton Absorption Wavelength (nin) —v Figure 11.12 Normalized TPA spectra (solid line curves) and linear absorption spectra (dot-dashed line curves) for five chromophores solution in THF [34]. (Reproduced with permission.)... 

Ohta et have investigated the molecular orientation effects on the TPA spectra, using J- and H-type dimers composed on three-state monomers. They have highlighted the structures that can lead to enhancement of the TPA intensities. 

Figure 8.8 ECD and TPCD and OPA and TPA spectra for Si and S2 states of R3MCP computed with FCHTIVG and FCHTIAH models. All spectra are convoluted with aLorentzian broadening of 0.05 eV and obtained by averaging with Boltzmann weights the spectra of the individual conformers. Units are dm moP 1 photon mol for both TPCD and TPA.

Rapid convergence at large alternation is expected on general grounds. The sufficiency of N = 14 oligomers for linear or TPA spectra of Hubbard and PPP chains with 5 > 0.6 follows in detail from molecular exciton theory [116]. The different shapes of PPP and Hubbard crossovers in Fig. 6.15 are due to different B states, which are in turn related to Vpp- in Eq. (7) B is an exciton in PPP theory [134] and evolves [116] to an excited dimer at 5 = 1, while B is a CT state [37] in Hubbard chains at 5 1. These possibilities for B are another generic feature of Eq. (7). Molecular PPP parameters place [133] PA on the correlated side, PS and PPV on the band side. 

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