Controlling intramolecular hydrogen migration by asymmetric laser fields: the water case.

Hydrogen and deuterium intramolecular migration in water's isotopomer dications has been found to depend on the wavelength of the laser used for the excitation. This is imprinted in H-2(+) and D-2(+) fragment ions' observation in the mass spectra induced by single color fs laser irradiation with 800 nm <= lambda <= 1570 nm. Based on these findings, experiments with omega/2 omega asymmetric laser fields (1400/700 nm) have been performed. The dissociation channels of the dications exhibit different dependence on the phase between the omega and 2 omega components of the field thus offering an ability for controlling the fragmentation. For the interpretation of these observations, a tunneling mechanism is invoked.