Komarova L. Vibrational mode chiral anisotropy of carbon and boron nitride nanotubes.

For the first time carbon and boron nitride single-walled nanotubes have been validly considered as one periodical crystal in new phonon state classification that has been confirmed by independent calculation of forms of fundamental normal vibrations. In particular it describes and interprets anomalous relation of intensities of first and second order lines in experimentally observed Raman spectra of carbon nanotubes. It has been determined that high-energy electron irradiation (Ее = 1.8 МeV) of multi-walled carbon nanotubes caused the changes of the D- and G-band structure as result of radiation-induced defect formation. In such kind of process carbon atoms shift into the interstitial site atom positions that promotes sewing together grafene layers of nanotubes. For the first time the investigation of Davydov splitting of the vibrational modes of monolayers in graphite and boron nitride single crystals with two translational non-equivalent layers in unit cells has been carried out. Davydov doublets in Raman and IR absorption spectra have been experimentally detected. The correlation diagrams determining correspondence between vibrational modes of monolayers and nanotubes have been built. The effect of chiral anisotropy of vibrational modes has been discovered. It reveals physical nature of doublet bands in Raman spectra of single-walled carbon and boron nitride nanotubes. It has been proved that the intensity relationship of chiral doublet components can be used for the carbon nanotube chiral content detection while the chiral splitting values - for estimation of their diameters.