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 CO bonds is discussed in terms of the nuclear dynamics in CO22+.