  We recently questioned the treatment of a dust particle as a perfect absorber
for electrons and ions and proposed a surface model for the charge of a dust
particle in a quiescent plasma which combines the microscopic physics at the
grain boundary (sticking into and desorption from external surface states) with
the macrophysics of the discharge (plasma collection fluxes). Within this model
the charge and partial screening of the particle can be calculated without
relying on the condition that the total electron collection flux balances on
the grain surface the total ion collection flux. Grain charges obtained from
our approach compared favorably with experimental data. The purpose of this
paper is to describe our model in more detail, in particular, the hypotheses on
which it is built, contrast it with the standard charging models based on flux
balancing on the grain surface, and to analyze additional experimental data.
