  We show, with both experiment and theory, that adsorption of $CO_2$ is
sensitive to charge on a capturing model carbonaceous surface. In the
experiment we dope superfluid helium droplets with $C_{60}$ and $CO_2$ and
expose them to ionising free electrons. Both positively and negatively charged
$C_{60}(CO_2)_n^{+/-}$ cluster ion distributions are observed with a
high-resolution mass spectrometer and these show remarkable and reproducible
anomalies in intensities that are strongly dependent on the charge. The highest
adsorption capacity is seen with $C_{60}^+$. Complementary density functional
theory calculations and molecular dynamics simulations provided insight into
the nature of the interaction of charged $C_{60}$ with $CO_2$ as well as trends
in the packing of $C_{60}^+$ and $C_{60}^-$. The quadrupole moment of $CO_2$
itself was seen to be decisive in determining the charge dependence of the
observed adsorption features. Our findings are expected to apply to adsorption
of $CO_2$ by charged surfaces in general.
