Scaling of wave-packet dynamics in an intense midinfrared field.

A theoretical investigation is presented that examines the wavelength scaling from near-visible (0.8 {mu}m) to midinfrared (2 {mu}m) of the photoelectron distribution and high harmonics generated by a 'single' atom in an intense electromagnetic field. The calculations use a numerical solution of the time-dependent Schroedinger equation (TDSE) in argon and the strong-field approximation in helium. The scaling of electron energies ({lambda}{sup 2}), harmonic cutoff ({lambda}{sup 2}), and attochirp ({lambda}{sup -1}) agree with classical mechanics, but it is found that, surprisingly, the harmonic yield follows a {lambda}{sup -(5-6)} scaling at constant intensity. In addition, the TDSE results reveal an unexpected contribution from higher-order returns of the rescattering electron wave packet.