Orientational effect of the texture of a carbon-nanotube film on CK$_\alpha$ a radiation intensity

The angular dependence of the intensity of CK$_\alpha$ radiation measured from a film of oriented carbon nanotubes shows an increase in the yield of x-ray fluorescence along the growth direction of the nanotubes. The angular distribution of the intensity of scattered x rays is close in magnitude to the angular distribution of the directivity of nanotubes in the film that is determined by analyzing an electron-microscope image. To explain the propagation of radiation along the nanotubes, two mechanisms are proposed on the basis of reflection from inner walls of a tube (channeling) and an anomalous dispersion of CK$_\alpha$ photons in the carbon medium.