Spin–orbit state-selective C–I dissociation dynamics of the CH3I+ x̃ electronic state induced by intense few-cycle laser fields

• Main Authors: Wei, Zhengrong, Li, Jialin, See, Soo Teck, Loh, Zhi-Heng
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2019
• Subjects: Dissociation Dynamics; Laser Fields; Science::Chemistry::Biochemistry
• Online Access: https://hdl.handle.net/10356/84898; http://hdl.handle.net/10220/49164
• Institution: Nanyang Technological University

Studies of ultrafast molecular dynamics induced by intense laser fields can reveal new approaches to manipulating chemical reactions in the strong-field regime. Here, we show that intense few-cycle laser pulses can induce the spin–orbit state-selective C–I dissociation of the iodomethane cation (CH3I+) in the X̃ electronic state. Irradiation of CH3I by 6 fs laser pulses with peak intensities of 1.9 × 1014 W/cm2 followed by femtosecond extreme ultraviolet probing of the iodine 4d core-level transitions reveals dissociation of the CH3I+X̃2E1/2 state with a time constant of 0.76 ± 0.16 ps. By contrast, the X̃2E3/2 spin–orbit ground state does not exhibit any appreciable dissociation on the picosecond time scale. The observed spin–orbit state-selective dissociation of the X̃ state is rationalized in terms of the laser-induced coupling to the à state. Our results suggest that the intense-laser control of photodissociation channels can be potentially extended to spin–orbit split states.