  For a one-dimensional electron-phonon system we consider the photon
absorption involving electronic excitations within the pseudogap energy range.
Within the adiabatic approximation for the electron - phonon interactions these
processes are described by nonlinear configurations of an instanton type. We
calculate intensities of the photoelectron spectroscopy PES including the
momentum resolved one ARPES and supplement to known results for the optical
subgap absorption. We start with the generic case of a one dimensional
semiconductor with pronounced polaronic effect. In details we consider the
Peierls model for a half-filled band of electrons coupled to the lattice which
describes the polyacethylene and some commensurate Charge Density Waves.
Particular attention was required for studies of momentum dependencies for the
ARPES where we face an intriguing interference between the time evolution and
the translational motion of the instantons.
