  We present a systematic angle-resolved photoemission spectroscopic study of
the high-Tc superconductor class (Sr/Ba){1-x}(K/Na)xFe2As2. By utilizing a
photon-energy-modulation contrast and scattering geometry we report the Fermi
surface and the momentum dependence of the superconducting gap, Delta(k). A
prominent quasiparticle dispersion kink reflecting strong scattering processes
is observed in a binding-energy range of 25-55 meV in the superconducting
state, and the coherence length or the extent of the Cooper pair wave function
is found to be about 20-angstrom, which is uncharacteristic of a
superconducting phase realized by the BCS-phonon-retardation mechanism. The
observed 40 meV kink likely reflects contributions from the frustrated spin
excitations and scattering from the soft phonons. Results taken collectively
provide direct clues to the nature of the pairing potential including an
internal phase-shift factor in the superconducting order parameter which leads
to a Brillouin zone node in a strong-coupling setting.
