High-order harmonic generation in alkanes: signature of the ground state wavefunction

In this work, XUV spectra from some alkanes (methane, I/sub p/ = 12.97 eV; propane, I/sub p/ = 11.07 eV; butane, I/sub p/ = 10.63 eV) are measured and compared with those acquired from xenon (I/sub p/ = 12.13 eV). The harmonic emission is obtained focusing femtosecond light pulses on a pulsed gas jet. Two different pulse durations are considered, namely 20 fs and 6 fs; in both cases the pulse energy could be continuously tuned without modification in temporal and spatial structure of the driving pulses. The experimental results have been compared to numerical simulation based on an atom-like Lewenstein model. Preliminary results reproduce the cutoff wavelength behavior of the investigated molecular species.