Tracking and controlling dissociative ionization of formic acid molecules by femtosecond laser fields.

This article focuses on the experimental investigation of the dissociative ionization of formic acid molecules using intense femtosecond laser pulses. By employing time-resolved pump–probe methods with two-color femtosecond laser fields at 800 nm and 400 nm, the study identifies two distinct fragmentation pathways producing ionic formyl (HCO⁺) and hydroxyl (OH⁺) radicals, characterized by high and low kinetic energy release (KER) regions. The research further demonstrates control over the spatial emission direction of these ionic fragments by adjusting the relative phase and polarization of the two-color laser pulses, attributing the observed asymmetries to molecular orbital profile-dominated ionization. These findings advance understanding of ultrafast fragmentation dynamics and directional bond breaking in polyatomic molecules under strong laser fields.