  The behavior of polyampholytes near a charged planar surface is studied by
means of Monte Carlo simulations. The investigated polyampholytes are overall
electrically neutral and made up of oppositely charged units (called blocks)
that are highly charged and of the the same length. The influence of block
length and substrate's surface-charge-density on the adsorption behavior is
addressed. A detailed structural study, including local monomer concentration,
monomer mean height, transversal chain size, interface-bond orientation
correlation, is provided. It is demonstrated that adsorption is favored for
long enough blocks and/or high enough Coulomb interface-ion couplings. By
explicitly measuring the chain size in the bulk, it is shown that the charged
interface induces either a swelling or a shrinkage of the transversal dimension
of the chain depending, in a non trivial manner, on the block length.
