The resonance behavior and the dispersion of the GЈ line in double-wall carbon nanotubes were investigated by multifrequency Raman scattering. Using a large number of laser lines for excitation, the dispersion for the response from the inner tubes and from the outer tubes was found to be 85 and 99 cm −1 / eV, respectively. The reduction of the dispersion for the inner tubes is a consequence of their high curvature and suggests a flattening of the phonon dispersion at the K point in the Brillouin zone. The frequency position for the GЈ line of the inner tubes for a given laser energy was likewise strongly reduced as compared to values expected from tubes with standard diameter. This was again assigned to the strong curvature of the small-diameter inner tubes. Finally, the GЈ line scattering cross sections for the outer tubes and for the inner tubes revealed resonances according to the transitions between the corresponding Van Hove singularities. The response from the inner tubes was particularly strong, in good agreement with the expected resonance enhancement resulting from their high curvature.

Nanowires (NWs) of metal oxides (Fe(2)O(3), CuO, V(2)O(5) and ZnO) were grown by an efficient non-catalytic economically favorable method based on resistive heating of pure metal wires or foils at ambient conditions. The growth rate of iron oxide NWs exceeds 100 nm s(-1). Produced NWs were typically 1-5 microm long with diameters from 10 to 50 nm. The produced metal oxide NWs were characterized by means of SEM, TEM, EDX, XPS and Raman techniques. The field emission measurements from the as-produced CuO NWs were found to have a threshold field as low as 4 V microm(-1) at 0.01 mA cm(-2). The formation mechanism of the NWs is discussed.

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Raman spectroscopy study of multi‐wall carbon nanotubes (MWNTs) of different diameters (with a small controllable number of walls) produced using Fe–Co catalyst with a variable size of the same active component has been performed. We have characterized as produced MWNTs with different diameters (series 1) and two types of tubes with fixed mean diameters (∼10 and 20 nm) heated in a flow of pure argon at various temperatures (2200, 2600 and 2800 °C – series 2). The Raman spectra of MWNTs have been registered in three spectral regions, corresponding to D (disorder‐induced), G (graphite) and 2D (two‐phonon scattering) bands. A ratio of intensities I2D/ID for tubes of series 1 has demonstrated almost a linear dependence on the nanotube diameter. After heating (series 2), D (disorder‐induced) Raman band has shown a substantial decrease in intensity. The variation of the Raman spectra parameters is discussed in terms of defectiveness of nanotubes.

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