  We present a theoretical study of atomic laser-assisted photoionization
emission (LAPE). We consider an atom driven by a linearly polarized XUV laser
in two different scenarios: i) a single attosecond pulse (in both the streaking
and sideband regimes) and ii) an attosecond pulse train. The process takes
place assisted by a linearly polarized infrared (IR) laser field. In all these
cases the energy and angle-resolved photoelectron spectrum (PES) is determined
by a leading contribution, related to the intracycle factor [Gramajo et al., J.
Phys. B 51, 055603 (2018)], complemented by other ones, derived from the
periodicity and symmetry properties of the dipole transition matrix with
respect to the IR field. Each of these terms imprint particular features in the
PES that can be straightforwardly understood in terms of generalized energy
conservation laws. We investigate in detail these PES structures, in
particular, for the case of argon initially in the 3s quantum state. Our
theoretical scheme, based on the strong-field approximation (SFA), can be
applied, however, to other atomic species and field configurations as well.
