  Various technical developments extended the potential of angle-resolved
photoemission (ARPES) tremendously during the last twenty years. In particular
improved momentum, energy and spin resolution as well as the use of photon
energies from few eV up to several keV makes ARPES a rather unique tool to
investigate the electronic properties of solids and surfaces. With our work we
present a generalization of the state of the art description of the
photoemission process, the so called one-step model that describes excitation,
transport to the surface and escape into the vacuum in a coherent way. In
particular, we present a theoretical description of temperature-dependent ARPES
with a special emphasis on spin fluctuations. Finite temperature effects are
included within the so called alloy analogy model which is based on the
coherent potential approximation and this way allows to describe uncorrelated
lattice vibrations in combination with spin fluctuations quantitatively on the
same level of accuracy. To demonstrate the applicability of our approach a
corresponding numerical analysis has been applied to spin- and angle-resolved
photoemission of Fe(100) at finite temperatures.
