Figure 2: Subfemtosecond directional control of deprotonation.

(a) Density plot of the momentum of H⁺ fragments as a function of CEP. CEP-integrated momenta are shown in the right panel. The dashed (dotted) lines shown correspond to CEP with maximum positive (negative) asymmetry in the ion emission, respectively. (b) Density plot for the asymmetry parameter, A(p_||,φ), for the H⁺ fragments. (c) The asymmetry parameter, A(φ), integrated over all momenta for H⁺ ions. The error bars were derived via error propagation using the s.d. in the ion yields with positive and negative momenta. The clear oscillation in the asymmetry for the directional emission of H⁺ fragments as a function of CEP under the given laser conditions demonstrates the CEP-control of the hydrogen emission direction. Also shown is the calculated asymmetry (solid red line) obtained from our quantum dynamical calculations (see text for details), which has been shifted in absolute CEP for best overlap with the experimental data since the absolute CEP is not known from the experiment.