Raman spectroscopic studies of amorphous carbon and buckminsterfullerene
Raman spectroscopic techniques have been applied to investigate a variety of carbon systems. Using resonance Raman spectroscopy as a probe for optical transitions in a system, a careful quantitative estimate of the Raman cross-section of graphite in the pre-resonance regime has been made. Raman and resonance Raman spectroscopy have been used to correlate the structural and electronic properties of amorphous carbon materials. The low optical gaps and e-2e spectroscopy measurements on evaporated carbon films suggests a structure close to graphite. Raman measurements, however, reveal a great amount of disorder in the material. This apparent contradiction has been resolved through the use of a phenomenological model for the electronic density of states for amorphous carbon systems. Raman spectroscopy has also been used to study the vibrational and the electronic properties of the recently discovered third allotrope of carbon, C[sub 60]. The vibrational modes of this molecule have been studied in great detail. The observed vibrational spectra confirms earlier work in this material. Furthermore, the mode frequencies have been found to be in reasonably good agreement with theoretical predictions. Resonance Raman studies of solid C[sub 60] and C[sub 60] dissolved in solvents has revealed, in the solid phase, the existence of optical transitions well below the symmetry allowed transitions for the isolated molecules. Loss of inversion symmetry in the solid state has been proposed to account for the resonance observed in the Raman excitation profile. Original Raman measurements on C[sub 60] revealed a strong peak at 1469 cm[sup [minus]1]. The peak was found to obey the correct selection rule for symmetric A[sub g] mode and was assigned to the [open quotes]pentagonal pinch[close quotes] mode of the molecule.
- Research Organization:
- Arizona State Univ., Tempe, AZ (United States)
- OSTI ID:
- 7243671
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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