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Using a 45 fs pump pulse at 800 nm, a wave packet is created in a charge asymmetric dissociation channel of iodine, I(2)(2+)→I(2+)+I(0+) (2,0). As the molecule dissociates, a two-color (1ω2ω) probe pulse is used to study the dynamics as a function of internuclear separation R. We find a critical region of R in which there is spatially asymmetric enhanced ionization of the (2,0) channel to a counterintuitive (1,2) channel. In this region the I(0+) is ionized such that one electron is released to the continuum and another is transferred to the I(2+) resulting in I(0+)→I(2+) and I(2+)→I(1+). At larger R, the ionization is consistent with simple one-electron ionization in a double well where I(0+)→I(1+). We find qualitative agreement between simulations and experiment further highlighting the importance of multielectron effects in the strong-field ionization of molecules.

We have designed a pump-probe experiment to excite I2 to the B state and subsequently ionize the molecule with a two-color (800 and 400 nm) probe pulse. By varying the relative phase of the two colors we are able to probe the asymmetric dissociation of I 2+ 2 → I2+ + I and we observe spatial asymmetries in the ion yield of this (2,0) channel. Because the durations (35 fs) of the pump and probe pulses are much shorter than the vibrational period of the B state (700 fs) we can fully resolve the dynamics as a function of internuclear separation R. We find that the amplitude of the spatial asymmetry increases as a function of R and that the relative phase of the two colors that produces the maximum asymmetry is independent of R. Both of these observations are consistent with ionization of I2 directly into the field-dressed potential curves of I 2+ 2 , which we model with a two-electron 1-D double-well potential in an external field. Interestingly, we find a spatial asymmetry for dissociation channels with a charge difference ∆q = 2, ((2,0) and (3,1)), but not for ∆q = 1, ((1,0), (2,1), (3,2)). Finally, substructure in the time-of-flight data shows two distinct states leading to the (2,0) dissociation limit, one of which may indicate a breakdown of the presented model.