  A single-walled carbon nanotube presents a seamless cylindrical graphene
surface and is thus an ideal adsorption substrate for investigating the physics
of atoms and molecules in two dimensions and approaching the one-dimensional
limit. When a suspended nanotube is made into a transistor, frequency shifts of
its mechanical resonances allow precise measurement of the adsorbed mass down
to the single-atom level. Here we show that its electrical characteristics are
also modified by the adsorbed atoms and molecules, partly as a result of a
small charge transfer between them and the carbon surface. We quantify this
charge transfer, finding it similar for many different species, and use the
associated sensitivity of the conductance to carry out studies of phase
transitions, critical scaling, dynamical fluctuations, and dissipative
metastable states in a system of interacting atoms confined to a cylindrical
geometry.
