Coherent Control of Photofragment Separation in the Dissociative Ionization of IBr

We have investigated coherent control of the dissociative ionization of IBr using phase-controlled two-color ω+2ω laser pulses with an intensity of 1.0×10¹² W/cm and a pulse duration of 130 fs. The directional asymmetries of the photofragment angular distributions showed oscillation behavior dependent on the relative phase difference between the ω and 2ω pulses. The phase dependencies of the directional asymmetries observed for iodine ions and bromine ions were out of phase with each other. This result shows that a phase-controlled ω+2ω optical field can produce molecular orientation in which the optical field discriminates between parallel and antiparallel configuration of molecules that have a permanent dipole.