High-order harmonic generation of 1-nonene under linearly polarized laser pulses

Abstract

High-order harmonic generation of the long-chain molecule 1-nonene (${\mathrm{C}}_{9}{\mathrm{H}}_{18}$) under a few-cycle linearly polarized laser field was studied using time-dependent density-functional theory. The efficiency and the cutoff frequency of the ${\mathrm{C}}_{9}{\mathrm{H}}_{18}$ harmonic spectrum are significantly higher than those of the BF molecule irradiated by the same laser pulse. By analyzing the time-frequency behavior of the harmonic and the classical simulation of electron, it is found that the ${\mathrm{C}}_{9}{\mathrm{H}}_{18}$ harmonics near the cutoff energy are caused by the recombination of electrons from one atom to others of the parent molecule. In addition, the high-order harmonic generation of the long-chain molecule 1,3-Butadiene (${\mathrm{C}}_{4}{\mathrm{H}}_{6}$) is also investigated. The harmonics generated by this mechanism can be applied to produce high-intensity isolated attosecond pulses.