The 397.9 nm, 416.0 nm and 435.7 nm resonance Raman spectra were acquired for meso-tetrakis(4-carboxyphenyl)porphyrin (TCPP) in tetrahydrofuran solution, and the Raman effect of relaxation dynamics was analyzed according to Herzberg-Teller (vibronic coupling) contributions. Density functional calculations were done to help the elucidation of the Soret (B(x) and B(y)-band) electronic transitions and the corresponding photo relaxation dynamics of TCPP. The spectra indicate that the Franck-Condon region photo relaxation dynamics upon S(0) → S(4) electronic transition are predominantly along the totally symmetric C(m)-ph stretch and Porphin ring breath stretch, and simultaneously along the asymmetric ν(C(m)-Phenyl) + δ(N-H) and ν(C(α)-C(m)-C(α))(as) + def (pyr) vibrational relaxation processes. The excited state structural dynamics of TCPP determined from the resonance Raman spectra show that the internal conversion between the B(y) and B(x) electronic states occurs in tens of femtoseconds, and the electronic relaxation dynamics were firstly interpreted taking into account the time-dependent wave packet theory and Herzberg-Teller (vibronic coupling) contributions.
Dimethyl 1,3-dithiole-2-thione-4,5-dicarboxylate (DDTD) was synthesized and characterized using NMR, Fourier transform (FT)-Raman, Fourier transform-infrared (FT-IR) and UV spectroscopies. Resonance Raman spectra (RRs) were obtained with 341.5, 354.7 and 368.9 nm excitation wavelengths and density functional calculations were carried out to elucidate the π (S-C-S) → π * (S-C-S) electronic transitions and the RRs of DDTD in cyclohexane solution. The RRs indicate that the Franck-Condon region photo dynamics have a multidimensional character with motion predominantly along the C S stretch and the C-S symmetric stretch modes in the five-member heterocycle. A preliminary resonance Raman intensity analysis was carried out and the results for DDTD were compared with previously reported results for 1,3-dithiole-2-thione (DTT). Differences and similarities of the spectra in terms of molecular symmetry and electron density are also discussed.
Resonance Raman (RR) spectra of free-base meso-tetra(p-hydroxyphenyl)porphine(THPP) were obtained with 397.9, 416 and 514 nm excitation wavelengths, and density functional calculations were carried out to help the elucidation of the photorelaxation dynamics of Soret (B x and B y bands) electronic transitions and the RR spectra of THPP. The RR spectrum indicates that the Franck-Condon (FC) region photorelaxation dynamics for the S 0 → S 5 excited electronic state is predominantly along the totally symmetric C m -phC stretching and the C β C β stretchingand simultaneously along the asymmetric (C m C α )as stretching, ν(phC C)asstretching, δ(NH)s and γ (C β H) vibrational relaxation processes, while that for S 0 → S 4 electronic state is predominantly along the C m -phC stretching and pyrrole breathing. The excited-state structural dynamics of THPP determined from the RR spectra shows that internal conversion (IC) B y → B x electronic relaxation occurs in tens of femtoseconds, and the short-time dynamics is interpreted using the time-dependent wave packet theory and Herzberg-Teller (vibronic coupling) contributions.
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