Interference between competing pathways in harmonic generation

We investigate the influence of the autoionizing 3s3p(6)nl resonances on the fifth harmonic generated by 200 - 240 nm laser fields interacting with Ar. To determine the influence of a multi-electron response we have developed capability within time dependent R-matrix theory to determine the harmonic spectra generated. The fifth harmonic is affected by interference between the response of a 3s electron and the response of a 3p electron, as demonstrated by the asymmetric profiles in the harmonic yields as functions of wavelength.