Toward the extension of high order harmonic spectroscopy to complex molecules: Investigation of aligned hydrocarbons

Abstract

High-order harmonic generation is as a powerful tool for the study of molecular properties. Up to now this investigation tool has been confined to simple molecules, with a relatively high ionization potential, since ionization saturation hindered its exploitation to fragile molecules. In this work we show that such limitation can be overcome by using mid-IR ultrashort driving pulses; as prototypical molecules we considered hydrocarbons. Clear signatures of the highest occupied molecular orbital were found in the harmonic spectra generated in unsaturated aligned hydrocarbons like acetylene, ethylene, allene and 1,3-butadiene. Our findings demonstrate that high-order harmonic generation spectroscopy can be extended to complex molecular species. © Springer-Verlag Berlin Heidelberg 2012.