Figure 1

(a) Model of DFDBrBPh and the laser geometry of the experiment. The molecule consists of a pair of phenyl rings. The substituted Br and F atoms are needed to identify the two rings in the experiment. (b) The torsional potential of DFDBrBPh [26]. The torsion is quantified by the dihedral angle, ${\varphi }_d$, between the two phenyl rings. The minima at dihedral angles of ${\varphi }_d=\pm 39°$ result in the $R_a$ and $S_a$ enantiomers (see text).Reuse & Permissions

Figure 2

(a) Ion images of ${\mathrm{F}}^{+}$ and ${\mathrm{Br}}^{+}$ fragments at probe times $t_p$. The ns pulse is polarized perpendicularly to the image (detector) plane and the $5\times {10}^{12}\mathrm{W}/{\mathrm{cm}}^2$, 700 fs (FWHM) kick pulse is polarized horizontally. (b) Angular distribution of the ${\mathrm{F}}^{+}$ ions, at $t_p=1.47\mathrm{ps}$, obtained by radially integrating the corresponding ${\mathrm{F}}^{+}$ ion image. The splitting of the pairwise peaks is twice the average angle, $⟨{\varphi }_{{\mathrm{F}}^{+}\mathrm{\text{−}}\mathrm{kick}.\mathrm{pol}}⟩$, between the ${\mathrm{F}}^{+}$ ion recoil and the kick pulse polarization. (c) $⟨{\varphi }_{{\mathrm{F}}^{+}\mathrm{\text{−}}\mathrm{kick}.\mathrm{pol}}⟩$ as a function of $t_p$, for times where a clear four-peak structure is visible in the angular distributions. The curve is a fit of the sum of a linear and a harmonic function to the experimental points (squares).Reuse & Permissions

Figure 3

Angular distributions of (a) F-phenyl and (b) Br-phenyl rings at $t_p=0.08$, 1.47, and 2.47 ps. (c) Expectation value of the dihedral angle for a molecule starting out with the SMPA aligned along the kick pulse polarization. The kick pulse is as in Fig. 2.Reuse & Permissions

Figure 4

Time evolution of the dihedral angle for a molecule starting out as (a) an ${\mathrm{R}}_a$ or (b) an $S_a$ enantiomer. Initially, the molecule is 3D oriented with the Br-phenyl end pointing out of the paper and the SMPA aligned at an angle of 13° with respect to the kick pulse polarization. The kick pulse triggering the torsional motion has a peak intensity of $1.2\times {10}^{13}\mathrm{W}/{\mathrm{cm}}^2$ and duration (FWHM) of 1.0 ps. The torsional barrier is reduced by $1/4$ rather than increasing the kick strength further. Such modification of the torsional potential may be accomplished by replacing DFDBrBPh with, e.g., halogen substituted biphenylacetylene.Reuse & Permissions