  The anomalous high-energy dispersion of the conductance band in the high-Tc
superconductor Pb-Bi2212 has been extensively mapped by angle-resolved
photoemission (ARPES) as a function of excitation energy in the range from 34
to 116 eV. Two distinctive types of dispersion behavior are observed around 0.6
eV binding energy, which alternate as a function of photon energy. The
continuous transitions observed between the two kinds of behavior near 50, 70,
and 90 eV photon energies allow to exclude the possibility that they originate
from the interplay between the bonding and antibonding bands. The effects of
three-dimensionality can also be excluded as a possible origin of the
excitation energy dependence, as the large period of the alterations is
inconsistent with the lattice constant in this material. We therefore confirm
that the strong photon energy dependence of the high-energy dispersion in
cuprates originates mainly from the photoemission matrix element that
suppresses the photocurrent in the center of the Brillouin zone.
