Controlling the interference of multiple molecular orbitals in high-harmonic generation

We demonstrate a new method to investigate the origin of spectral structures in high-harmonic generation. We report detailed measurements of high-harmonic spectra in aligned nitrogen and carbon dioxide molecules. Varying the wavelength and intensity of the generating laser field, we show that the minimum in aligned N2 molecules is nearly unaffected, whereas the minimum in aligned CO2 molecules shifts over more than 15 eV. Our quantitative analysis shows that both the interference of multiple orbitals and their structural characteristics affect the position of the minimum. Our method provides a simple approach to the investigation of the high-harmonic generation process in more complex molecules.Nous faisons la d\ue9monstration d\u2019une nouvelle m\ue9thode pour \ue9tudier l\u2019origine des structures spectrales lors de la production d\u2019harmoniques \ue9lev\ue9es. Nous donnons les mesures d\ue9taill\ue9es de spectre \ue0 grande teneur en harmoniques d\u2019ordre \ue9lev\ue9 dans des mol\ue9cules align\ue9es d\u2019azote et de dioxyde de carbone. En faisant varier la longueur d\u2019onde et l\u2019intensit\ue9 du champ laser g\ue9n\ue9rateur, nous montrons que cela n\u2019a presque aucun effet sur le minimum obtenu des mol\ue9cules de N2 align\ue9es, alors que le minimum des mol\ue9cules de CO2 align\ue9es passe \ue0 plus de 15 eV. Notre analyse quantitative montre que l\u2019interf\ue9rence d\u2019orbites multiples et de leurs caract\ue9ristiques structurelles a une incidence sur la position du minimum. Notre m\ue9thode constitue un moyen simple pour \ue9tudier le processus de g\ue9n\ue9ration d\u2019harmoniques \ue9lev\ue9es dans des mol\ue9cules plus complexes.Peer reviewed: YesNRC publication: Ye