Features of high order harmonic generation in the 30 fs and in the sub-10 fs regimes

Spectra of high-order harmonics, generated by 30 fs and sub-10 fs laser pulses in neon and krypton, have been obtained. The main characteristics of the measured spectra are analysed and discussed. For the 30 fs regime experimental results are compared with spectra calculated by means of a 1D propagation code which partially accounts for 3D focusing effects.