Coincidence momentum imaging of asymmetric Coulomb explosion of CO₂ in phase-locked two-color intense laser fields

Coulomb explosion of CO₂, CO₂ → CO22+ + 2e^- → CO⁺ + O⁺ + 2e^-, in phase-locked two-color ultrashort intense laser fields (800 nm and 400 nm, ∼10¹⁴ W/cm²) has been investigated by coincidence momentum imaging. The momentum images of the O⁺ and CO⁺ fragments show asymmetric distributions along the laser polarization direction depending on the relative phase of the two-color laser fields. The fragment asymmetry becomes most prominent (∼4%) at the relative phases providing the largest asymmetry of the electric field amplitude, with the O⁺ fragments preferentially ejected to the stronger field side. The mechanism of the asymmetric bond breaking of the two equivalent C-O bonds is discussed in terms of the nuclear dynamics in CO₂²⁺.