  The acceleration of ions from ultra-thin foils has been investigated using
250 TW, sub-ps laser pulses, focused on target at intensities up to
$3\times10^{20} \Wcm2$. The ion spectra show the appearance of narrow band
features for proton and Carbon peaked at higher energy (in the 5-10 MeV/nucleon
range) and with significantly higher flux than previously reported. The
spectral features, and their scaling with laser and target parameters, provide
evidence of a multispecies scenario of Radiation Pressure Acceleration in the
Light Sail mode, as confirmed by analytical estimates and 2D Particle In Cell
simulations. The scaling indicates that monoenergetic peaks with more than 100
MeV/nucleon energies are obtainable with moderate improvements of the target
and laser characteristics, which are within reach of ongoing technical
developments.
