  The effect of a N2 impurity on the radial thermal expansion coefficient (ar)
of single-walled carbon nanotube bundles has been investigated in the
temperature interval 2.2 - 43 K by the dilatometric method. Saturation of
nanotube bundles with N2 caused a sharp increase in the positive magnitudes of
ar in the whole range of temperatures used and a very high and wide maximum in
the thermal expansion coefficient (ar)(T) at T about 28 K. The low temperature
desorption of the impurity from the N2-saturated powder of bundles of
single-walled carbon nanotubes with open and closed ends has been investigated.
