National Research Council of Canada. Security and Disruptive Technologies
aromatic compounds; aromatization; harmonic analysis; molecular orbitals; molecular orientation; organic pollutants; thiophene; aromatic molecules; electron delocalization; five-membered rings; high order harmonic generation; high order harmonics; organic molecules; relative strength; strong field ionization; harmonic generation
The influence of cyclic electron delocalization associated with aromaticity on the high-order-harmonic generation (HHG) process is investigated in organic molecules. We show that the aromatic molecules benzene (C6H6) and furan (C4H4O) produce high-order harmonics more efficiently than nonaromatic systems having the same ring structure. We also demonstrate that the relative strength of plateau harmonics is sensitive to the aromaticity in five-membered-ring molecules using furan, pyrrole (C4H4NH), and thiophene (C4H4S). Numerical time-dependent Schrödinger equation simulations of total orientation-averaged strong-field ionization yields show that the HHG from aromatic molecules comes predominantly from the two highest π molecular orbitals, which contribute to the aromatic character of the systems.