Recollision-induced dissociation and ionization of oxygen in few-cycle laser fields

A correlated pair of an electron and its parent ion is generated when a molecule is irradiated by an intense laser pulse. The accelerated electron will be driven back when the laser's electric field changes its sign and it may collide with the parent ion. In the present work, we experimentally study the electron-ion recollision process of oxygen in few-cycle laser fields. Two reaction channels are identified through coincident measurements. One is initiated by the recollision-induced dissociation and the other by the recollision-induced ionization. Angular distributions of the atomic ions are also measured for these two reaction channels. Although the angular distributions are mainly determined by angle-dependent ionization rates of molecules, we find that they are also affected by the symmetry of the recollision-related molecular orbitals.