Energetic Materials Photolysis Footprint in High-Order Harmonic Generation

Photolysis of energetic materials offers safer and more controllable advantages compared to traditional ignition methods. Tracking the group and electron dynamics during the photolysis of energetic materials is currently a hot and challenging topic. In this work, we used a time-dependent density functional theory (TDDFT) to study the high-order Harmonic generation (HHG) dynamics induced by strong laser interaction with an isolated CH₃NO₂ molecule with varying C-N bond lengths. We found that the elongation of the C-N bond leaves a footprint on the corresponding HHG spectrum. One observed phenomenon is that the overall HHG cutoff position increases with the C-N bond length, and another is a sudden decrease in HHG efficiency at a certain bond length. Our analysis shows that this efficiency drop is due to changes in the electron recombination quantum paths caused by the C-N bond length alteration. Our research provides a new approach to tracking the photolysis process of energetic materials.