  Linear atomic chains containing a single Kondo atom, Co, and several
nonmagnetic atoms, Cu, were assembled atom by atom on Cu(111) with the tip of a
scanning tunneling microscope. The resulting one-dimensional wires,
Cu$_m$CoCu$_n$ ($0\leq m, n\leq 5$), exhibit a rich evolution of the single-Co
Kondo effect with the variation of $m$ and $n$, as inferred from changes in the
line shape of the Abrikosov-Suhl-Kondo resonance. The most striking result is
the quenching of the resonance in CuCoCu$_2$ and Cu$_2$CoCu$_2$ clusters.
State-of-the-art first-principles calculations were performed to unravel
possible microscopic origins of the remarkable experimental observations.
