Resonance Raman spectra of C70 in benzene

Gallagher, Sean H.; Armstrong, Robert S.; Lay, Peter A.; Reed, Christopher A.

doi:10.1016/0009-2614(95)00025-y

Cited by 8 publications

(37 citation statements)

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“…The positions of each of the laser lines relative to the electronic absorption spectrum of C 60 in benzene are given in Figure 1, and typical RR spectra of C 60 in benzene are shown in Figure 2. The REPs at the laser excitation wavelengths of 514.5, 496.5, 488.0, 476.5, 457.9, 413.1, and 406.7 nm for the bands due to the H g (1), A g (1), G g (4), H g (7), and A g (2) vibrational modes of C 60 at 264, 490, 1140, 1421, and 1468 cm -1 , respectively, are presented in Figure 3. The most notable result is the greater intensity of the bands of these five Raman modes at 413.1-and 406.7-nm excitation.…”

Section: Resultsmentioning

confidence: 99%

“…The first correction involved the "ν 4 " correction for the dependence of the intensity of the Raman band on the fourth power of the absolute energy. This was performed by comparing the benzene solvent band at 605 cm -1 with the H g (1) band at 264 cm -1 and the A g (1) band at 490 cm -1 , and the solvent band at 1568 cm -1 with the G g (4), H g (7), and A g (2) vibrational bands at 1140, 1421, and 1468 cm -1 , respectively. Equation 1 was used to calculate this effect where E L is the energy of the laser line, E S is the energy of the reference solvent band, and E V is the energy of the C 60 Raman band.…”

Section: Methodsmentioning

confidence: 99%

“…In both of these studies the C 60 samples were contaminated with C 70 , which has three strong Raman bands (between 1446 and 1470 cm -1 ) with large intensity enhancements at the excitation frequencies used in these experiments. 7 In another paper, McGlashen et al 5 have described the use of RR spectroscopy to investigate the change in wavenumber of the band due to the A g (2) pentagonal pinch mode of C 60 in solution upon reduction to C 60 1-. It was not until the HOMO-LUMO transition and its vibronic sideband were probed by us that substantial information on the resonance behavior of bands due to the non-totally-symmetric H g modes was obtained.…”

Section: Introductionmentioning

confidence: 99%

“…It was not until the HOMO-LUMO transition and its vibronic sideband were probed by us that substantial information on the resonance behavior of bands due to the non-totally-symmetric H g modes was obtained. 1,6 The H g (7) vibrational mode at 1421 cm -1 receives intensity enhancement through rare D-term scattering, which arises from non-adiabatic vibronic coupling of the LUMO of C 60 with the excited state of the higher energy C (3 1 T 1u -1 1 A g ) transition. 6 Most recently, a RR study of the spectrum of C 60 in a number of solvents revealed that the symmetry of C 60 is sensitive to its solvent environment, giving rise to a proliferation of bands arising from I h IR-active/Raman-silent and I h IR/Raman-silent vibrational modes.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we present the Raman excitation profiles (REPs) at seven laser wavelengths between 514.5 and 406.7 nm for the five most intense Raman bands of C 60 in solution, due to the H g (1), A g (1), G g (4), H g (7), and A g (2) vibrational modes. The REPs provide invaluable information on the different lightscattering mechanisms that operate, on the nature of the resonant electronic excited states, and on the nature of the vibrational modes.…”

Section: Introductionmentioning

confidence: 99%

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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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