  Electronic evolution from an antiferromagnet to a high-Tc superconductor is
revealed by angle-resolved photoemission experiments on tetragonal
Ca(1.9)Na(0.1)CuO(2)Cl(2) single crystals, which were successfully grown for
the first time under high pressures. In this underdoped superconductor, we
found clear fingerprints of the parent insulator: a shadow band and a large
pseudo-gap. These observations are most likely described by a "chemical
potential shift", which contrasts clearly with the prevailing wisdom of the
"pinned chemical potential" learned from the prototype La(2-x)Sr(x)CuO(4),
demonstrating that the route to a high-Tc superconductor is not unique.
