The real-space signatures from time-resolved electron diffraction investigations of structural dynamics are conveniently represented by ∆PDF(r, t), the difference between a timedependent PDF(r, t) and the static PDF(r). An isolated atomic distance change at time t, moving intensity in the PDF(r, t) from a distance r1 to a new distance r2, appears as a combination of a negative contribution to the ∆PDF(r, t) at r1 and a positive contribution at r2. We demonstrate such signatures with simulated ∆PDF signatures from equilibrium geometries of the three possible isomers of the electrocyclic ring-opening product hexatriene in Fig. . The structural differences between reactant and ring-opening products are dominated by the carbon-carbon distance of the bond, which is broken during the ring-opening in the first coordination sphere of CHD (labeled as R1 in Fig. ) and two additional distances in the second carbon coordination sphere of CHD (labeled as R2 in Fig. ). These distances assume, dependent on the isomer, different values above 3 Å in the photoproduct, which are indicated with color-coded arrows in Fig. . The resulting simulated ∆PDFs show negative signatures at the initial distance values in CHD and positive signatures at distance values above 3 Å.