observe the longitudinal structure of nanotubes, they are simply
dispersed in ethanol, and some droplets are deposited on a holey
carbon foil supported on a metal grid.
oxide nanotubes on a carbon foil (grey contrast) with large
you are looking for nanotubes in a sample that contains none, you nevertheless
might find some. The amorphous carbon foil on TEM grids is usually prepared
by arc-discharge between graphite electrodes under similar conditions that
also generate carbon nanotubes (CNTs). Thus, there are frequently some
nanotubes and onions of carbon present on the TEM grids. If there
is only a small
amount of tubular material present in the sample, one has to check
thoroughly if this really is the investigated material. There are
some examples in the literature, where CNTs are sold as novel nanotubes
of a different material!
CNTs found in a sample that contains no tubes at all.