No abstract

Multi-walled carbon nanotubes (MWNTs) of various diameters have been analyzed by Raman spectroscopy to clarify the influence of the diameter of MWNTs on their Raman spectra. The G-band frequency of MWNTs determined by curve fitting decreases with increasing tube diameter for diameters less than around 20 nm, beyond which it is almost constant. We believe that the G-band frequency of MWNTs with diameters less than 20 nm is affected by the interlayer spacing of MWNTs, and the behavior of the G-band frequency of MWNTs with diameters exceeding 20 nm can be explained on the basis of the optical penetration depth in graphite.

No abstract

Methylviologen dications (MV2+) were immobilized between layers of manganese oxide during their electrochemical assembly by an anodic route in a homogeneous aqueous Mn2+ solution. This approach yielded a well-ordered multilayer film on a platinum substrate as a result of dense packing of planar MV2+ molecules to stabilize the layered framework. A grazing angle in-plane X-ray diffraction study revealed that the manganese oxide sheets and the molecular planes of inserted MV2+ ions are oriented parallel to the electrode surface. Cyclic voltammetry of the product film indicated an electron transfer from the underlying Pt substrate to inserted methylviologen ions through the manganese oxide sheets.