  The electronic band structure of a liquid metal was investigated by measuring
precisely the evolution of angle-resolved photoelectron spectra during the
melting of a Pb monolayer on a Si(111) surface. We found that the liquid
monolayer exhibits a free-electron-like band and it undergoes a coherent radial
scattering, imposed by the radial correlation of constituent atoms, to form a
characteristic secondary hole band. This unique double radial bands and their
gradual evolution during melting can be quantitatively reproduced, including
detailed spectral intensity profiles, with our radial scattering model based on
a theoretical prediction of 1962. Our result establishes the radial band
structure as a key concept for describing the nature of electrons in strongly
disordered states of matter.
