Strong field physics in a scaled interaction

Strong-field interactions at long wavelengths are studied experimentally an d theoretically, and compared with studies at shorter wavelengths. Under si milar dynamical conditions, we find a more pronounced role for atomic struc ture in the long wavelength studies. Ion core structure is reflected in pho toelectron energy spectra in a manner consistent with the rescattering pict ure, and stronger coupling between ground and excited states influences hig h harmonic generation spectra. Spectral and temporal measurements of high h armonics generated from a mid-infrared fundamental are presented.