Structural characterization and potential x-ray waveguiding of a small rolled-up nanotube with a large number of windings

The cross-section of an InGaAs∕GaAs rolled-up nanotube with an average inner diameter of 18nm and with a large number of windings is prepared by focused ion beam etching and investigated by transmission electron microscopy. This technique provides useful information about the shape and size of the inner as well as outer perimeter of the nanotube. The measured cross-section geometry was used to calculate the mode confinement for hard x-ray radiation inside the tube. The authors find excellent confinement for the fundamental mode inside an idealized as well as the realistic tube structure. Their results imply that rolled-up nanotubes are promising candidates for x-ray waveguiding.