Dynamic Interference Of The High Harmonics From Photoisomerizing 1,3-Cyclohexadiene

The ionization potential difference between photoexcited and ground-state molecules results in a phase difference between their high harmonics, which causes high harmonic interference. The interference enables us to reveal how ionization potential of the photoexcited molecules evolves along the electronic relaxation path from the Franck-Condon state to the electronic ground state. We observe the ultrafast electron dynamics of a photoisomerizing molecule, 1,3-cyclohexadiene, via high harmonic interference. The experimental observations reveal that the electronic relaxation of 1,3-cyclohexadiene takes 200 fs, and the photoisomerization to 1, 3, 5-hexatriene takes an additional 450 fs. (C) 2021 Optical Society of America