experienced impressive progress during the last few decades [@Pas08]. The versatility of laser pulses has increased remarkably, thus allowing one to shape a wide range of dynamical scenarios in the course of irradiation processes. We briefly remind here key quantities of the laser pulses we are going to use in the following. Throughout this paper, we shall work in the dipole approximation which requires that the irradiated system is much smaller than the laser wavelength $\lambda= 2\pi c/\omega_\mathrm{las}$. In practice, the dipole approximation is well justified in the optical domain ($\lambda \sim
\mu$m) for systems of nm size. It may become questionable for XUV photons and very large clusters in which field variations [*inside*]{} the system itself should be accounted for. But we shall not consider such cases here. In the non-relativistic regime, linearly polarized laser pulses acting on atoms, molecules or clusters can then be described as a homogeneous time-dependent electric field of the form $$\mathbf{E}(t) 
  = 
  \mathbf{e}_\mathrm{pol} \, E_0 \, f(t) \, \sin(\omega_\mathrm{las}t 
  + 
  \varphi) 
  \quad.
\label{eq:Elaser}$$ In this expression, $\mathbf{e}_\mathrm{pol}$ denotes the (linear) polarization, $E_0$ is the peak field strength, $\omega_\mathrm{las}$ is the photon frequency, and $\varphi(t)$ is some phase shift, usually assumed to be zero. Finally 