Strong fields induce ultrafast rearrangement of H atoms in H2O

H atoms in H(2)O are rearranged by strong optical fields generated by intense 9.3 fs laser pulses to form H(2)(+). This atomic rearrangement is ultrafast: It occurs within a single laser pulse. Quantum-chemical calculations reveal that H(2)(+) originates in the (1)A state of H(2)O(2+) when the O-H bond elongates to 1.15 a.u. and the H-O-H angle becomes 120 degrees. Bond formation on the ultrafast time scale of molecular vibrations (10 fs for H(2)(+)) and in strong fields has hitherto not been reported.