Triplet state Raman spectra of C60 and C70

Jeoung, Sae Chae; Kim, Dongho; Kim, Sunae; Kim, Seong Keun

doi:10.1016/0009-2614(95)00671-p

Cited by 7 publications

(6 citation statements)

References 37 publications

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“…From group theory for vibronic coupling, an E 2 g vibration can couple the excited states of e 1 u orbital symmetry in a solvent-distorted C 60 . Independently, Jeoung et al . have attributed new bands arising in the triplet-state Raman spectra of C 60 in toluene solution to symmetry reduction in the electronic excited state.…”

Section: Discussionmentioning

confidence: 99%

Resonance Raman Scattering from Solutions of C₆₀

et al. 1997

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The resonance Raman (RR) spectrum of C60 has been studied in benzene and carbon disulfide using eight excitation wavelengths between 406.7 and 647.1 nm. Raman excitation profile calculations have been performed on the five most intense RR bands; the Hg(1), Ag(1), Gg(4), Hg(7), and Ag(2) vibrational modes. Two main scattering mechanisms predominate, Herzberg−Teller (HT) B-term scattering and nonadiabatic D-term scattering. This is the first observation of rare D-term scattering in a system without a metal. The requirement of a Jahn−Teller distortion of the excited state, produced upon population of the degenerate T1u LUMO, is essentially negated by solvent distortion of the symmetry of C60. While the I h point group is a good descriptor for the 10 fundamental Raman modes of C60, the slight reduction in the high symmetry of the molecule, due to solvent and 13C effects, activates at least 6 of the remaining 36 Raman-silent modes. At resonance with the HOMO−LUMO transition of C60, or its vibronic sideband, the solution resonance Raman spectra of C60 display almost the full gamut of RR scattering phenomena with no fewer than 13 distinct classes of first- and second-order vibrational features. The intensity behavior and the depolarization ratio of the band due to the I h -Raman-silent Gg(4) mode at 1140 cm-1 suggest that the distorted excited state is best approximated as having D 5 d symmetry. The presence of overtones and combinations of Raman-active and Raman-silent vibrational modes is explained in terms of a second-order HT scattering. These studies of the RR spectroscopy of C60 in solution have implications for the electron-pairing mechanism in the superconductivity of fullerides and the nature of solute−solvent associations such as between water-soluble derivatives of C60 and HIV-1 protease.

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Section: Discussionmentioning

confidence: 99%

Resonance Raman Scattering from Solutions of C₆₀

et al. 1997

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“…Several electronic transitions which are responsible for the deactivation of photoexcited Ru II porphyrins can be considered: first, the (π,d) transition from the HOMO of the ring to the unfilled metal d orbitals; second, the (d,d) transition between d orbitals of Ru II metal; third, the (d π ,π*(L)) transition from the metal d π electron to the axial ligand; finally, the (d π ,π*(ring)) transition from the metal d π electron to the ring e g (π*). The shift in opposite directions of the ν 4 mode for photoexcited Ru(II) porphyrins compared to photoexcited Cu II porphyrins 6a,b suggests that the excited state of Ru II porphyrins responsible for the observed Raman spectral features is different from the (π,d) or (d,d) state of Cu II porphyrins, which was suggested as the lowest excited state in Cu II porphyrins. 6a, In addition, the ligand-field splitting in Ru II is too large to invoke the (d,d) state 1a,b as an explanation for the excited state Raman spectrum.…”

Section: Resultsmentioning

confidence: 93%

“…The weak enhancement of the φ 4 (phenyl) and ν 1 modes suggests that the contribution from the T 1 (π,π*) states of Ru II TPP(L) 2 (L = pyridine and piperidine) to the excited state Raman spectra in Figures c, c, and 4c is negligible, because the strong enhancement of these two modes is characteristic for the porphyrin ring T 1 (π,π*) states of Zn II TPP, H 2 TPP, and Cu II TPP. 6a, Our proposition is in accord with the previous transient absorption measurements 4 in which the proposed lowest excited state of Ru II porphyrins is not the T 1 (π,π*) state but the charge transfer (CT) state.…”

Section: Resultsmentioning

confidence: 94%

Transient Raman Spectroscopic Investigations on Ru^IITPP(L)₂ (L = Pyridine and Piperidine) and Ru^IITPP(CO)(py) in Various Solvents: Alternation of Excited Charge Transfer Depending on Axial Ligation

Jeoung

Kim²,

Cho

et al. 1996

J. Phys. Chem.

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Transient Raman spectra with an excitation of nanosecond pulses at 416 nm were first recorded for Ru II TPP(L) 2 (L ) pyridine and piperidine) and Ru II TPP(CO)(py) in various solvents such as benzene, tetrahydrofuran, pyridine, and piperidine. This work is intended to investigate the nature of the charge transfer states accompanied by photoexcitation. It was found that the electronic structure of the lowest energy charge transfer (CT) state is largely dependent on not only the nature of axial ligands attached to the central metal but also the solvents employed. As for Ru II TPP(L) 2 (L ) pyridine and piperidine) in neat pyridine and piperidine solvents, the transient species were observed to be different in structure depending on the axial ligand. Several reasons for this observation were considered, including the discussion on the nature of the CT states such as (π,d), (d,d), (d π ,π*(L)) (L ) axial ligand), and (d π ,π*(ring)) states, and the configuration interaction between the two e g (π*) orbitals. The present transient Raman spectroscopic studies on photoexcited Ru II TPP(pip) 2 has manifested the Jahn-Teller effects, which may result in a diamond distortion of the porphyrin ring superimposed by a minor rectangular distortion. This major B 2g distortion accounts for the observation of a variety of unusual Raman spectral features in photoexcited Ru II TPP(pip) 2 . Meanwhile, the introduction of a CO ligand to Ru II porphyrin also altered the nature of the CT state in nonligating and weakly ligating solvents. It was observed that the CO ligand of the carbonylated Ru II porphyrin was substantially replaced by the solvent molecules such as pyridine and piperidine in the excited state. These experimental results were interpreted in terms of the change in the charge distribution among the porphyrin ring, the central metal and the axial ligand in the metal-to-ring (d π ,e g (π*)) CT state. The relevance of our findings to the photodynamics observed by the previous picosecond transient absorption measurements of photoexcited Ru(II) porphyrins is discussed in terms of the conformational changes of photoexcited species.

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“…During spin pumping, the normal Ag(2) mode of C 60 on Py is quenched, with vibrations transferred to duplicates at 1,445–1,460 cm −1 . These modes are associated with the spin triplet or magnetized state of C 60 39 , 40 , and can be observed during surface or tip enhanced spectroscopy 41 , 42 . Estimating the molecular population at each vibrational peak, the red shift comparing the vibrational peak for C 60 on Py off and on resonance during spin pumping translates into an average deceleration of the Ag(2) mode of 0.15 THz.…”

Section: Resultsmentioning

confidence: 99%

Optical conversion of pure spin currents in hybrid molecular devices

et al. 2017

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Carbon-based molecules offer unparalleled potential for THz and optical devices controlled by pure spin currents: a low-dissipation flow of electronic spins with no net charge displacement. However, the research so far has been focused on the electrical conversion of the spin imbalance, where molecular materials are used to mimic their crystalline counterparts. Here, we use spin currents to access the molecular dynamics and optical properties of a fullerene layer. The spin mixing conductance across Py/C60 interfaces is increased by 10% (5 × 1018 m−2) under optical irradiation. Measurements show up to a 30% higher light absorbance and a factor of 2 larger photoemission during spin pumping. We also observe a 0.15 THz slowdown and a narrowing of the vibrational peaks. The effects are attributed to changes in the non-radiative damping and energy transfer. This opens new research paths in hybrid magneto-molecular optoelectronics, and the optical detection of spin physics in these materials.

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Triplet state Raman spectra of C60 and C70

Cited by 7 publications

References 37 publications

Resonance Raman Scattering from Solutions of C₆₀

Resonance Raman Scattering from Solutions of C₆₀

Transient Raman Spectroscopic Investigations on Ru^IITPP(L)₂ (L = Pyridine and Piperidine) and Ru^IITPP(CO)(py) in Various Solvents: Alternation of Excited Charge Transfer Depending on Axial Ligation

Optical conversion of pure spin currents in hybrid molecular devices

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Triplet state Raman spectra of C60 and C70

Cited by 7 publications

References 37 publications

Resonance Raman Scattering from Solutions of C60

Resonance Raman Scattering from Solutions of C60

Transient Raman Spectroscopic Investigations on RuIITPP(L)2 (L = Pyridine and Piperidine) and RuIITPP(CO)(py) in Various Solvents: Alternation of Excited Charge Transfer Depending on Axial Ligation

Optical conversion of pure spin currents in hybrid molecular devices

Contact Info

Product

Resources

About

Resonance Raman Scattering from Solutions of C₆₀

Resonance Raman Scattering from Solutions of C₆₀

Transient Raman Spectroscopic Investigations on Ru^IITPP(L)₂ (L = Pyridine and Piperidine) and Ru^IITPP(CO)(py) in Various Solvents: Alternation of Excited Charge Transfer Depending on Axial Ligation