Ab initio investigation of the phase lag in coherent control of H(2)

An ab initio investigation of the excitation of an H(2) resonance, coupled to ionization and dissociation continua, was performed. The excitation occurs via a one- and a three-photon path where both fields have a variable but well-defined phase relation. While both continuum yields show an oscillatory behavior as the phase is varied, a pronounced phase lag between the two oscillations is observed, if the excitation energy is detuned from the resonant transition. The results are discussed in connection to a recent series of experiments performed on HI and the subsequent discussion on the possible origin of the observed phase lag.