  Magnesium atoms fully embedded in helium nanodroplets are exposed to
two-color laser pulses in order to exemplarily study the contribution of a
dense and finite medium on multiphoton-triggered above-threshold ionization
(ATI). The angular-resolved photoelectron spectra show striking differences
with respect to results obtained on free atoms. Scattering of the Mg
photoelectrons, when traversing the helium environment, causes the angular
distribution to become almost isotropic. Furthermore, we observe a marked
increase in the ATI order, pointing out the impact of the helium environment on
the concerted electron emission process. Phase-of-the-phase spectroscopy,
however, reveals a marked loss in the $2\omega-\omega$ phase dependence of the
electron signal. Taking into account sideband formation on a quantitative
level, a Monte-Carlo simulation which includes laser-assisted electron
scattering can reproduce the experimental spectra and give insights into the
strong field-induced electron emission from disordered systems.
