1,147 research outputs found
On the semi-classical analysis of the groundstate energy of the Dirichlet Pauli operator in non-simply connected domains
We consider the Dirichlet Pauli operator in bounded connected domains in the
plane, with a semi-classical parameter. We show, in particular, that the ground
state energy of this Pauli operator will be exponentially small as the
semi-classical parameter tends to zero and estimate this decay rate. This
extends our results, discussing the results of a recent paper by
Ekholm--Kova\v{r}\'ik--Portmann, to include also non-simply connected domains.Comment: 15 pages, 4 figure
The effect of O2 impurities on the low temperature radial thermal expansion of bundles of closed single-walled carbon nanotubes
The effect of oxygen impurities upon the radial thermal expansion (ar) of
bundles of closed single-walled carbon nanotubes has been investigated in the
temperature interval 2.2-48 K by the dilatometric method. Saturation of bundles
of nanotubes with oxygen caused an increase in the positive ar-values in the
whole interval of temperatures used. Also, several peaks appeared in the
temperature dependence ar(T) above 20 K. The low temperature desorption of
oxygen from powders consisting of bundles of single-walled nanotubes with open
and closed ends has been investigatedComment: 7 pages, 3 figure
Quantum effects in the radial thermal expansion of bundles of single-walled carbon nanotubes doped with 4He
The radial thermal expansion (ar) of bundles of single-walled carbon
nanotubes saturated with 4He impurities to the molar concentration 9.4% has
been investigated in the interval 2.5-9.5 K using the dilatometric method. In
the interval 2.1-3.7 K (ar) is negative and is several times higher than the
negative (ar) for pure nanotube bundles. This most likely points to 4He atom
tunneling between different positions in the nanotube bundle system. The excess
expansion was reduced with decreasing 4He concentration.Comment: 4 pages, 1 figure, will be published in Fiz.Nizk Temp. #7, 201
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