Observation of the phase lags among the molecules in the coherent phase control of multiphoton ionization

The phase lags among the molecules have been observed in the coherent phase control of multiphoton ionization. Coherent phase control using three- and one-photon excitation scheme has been applied to the multiphoton ionization of the (CH3)3N, (CH3)2S, C2H5SH, CH3I, and CD3I molecules. The phase lags of methyliodide (CH3I and CD3I) relative to other molecules showed considerable dependence on the excitation wavelength, especially in the vicinity of the absorption peak of CD3I. The energy dependence of the phase lag indicates that the molecular phase for the ionization of methyliodide is not zero.