  The sudden change of the velocity, so-called "kink," of the dispersing peak
in angle resolved photoelectron spectroscopy is a well-known feature in the
high temperature superconducting cuprates. Currently, the origin of the kink is
being much debated, but a consensus has not emerged yet. Here, we present a
study of the momentum evolution of the kink structure from the nodal region
towards the anti-nodal region, for optimally doped Bi2212 sample. We show that
the observed temperature dependence of the kink structure in both regions of
the momentum space is consistent with a scenario in which phonons contribute
strongly to the kink.
