Fig. 2: XFEL diffraction results showing time evolution of g = 200 reflections from the polypropylene-olivine-Al₂O₃ layered target.

a Two dimensional images where each number represents the delay time t of an XFEL pulse from the power laser pulse arrival time to the surface of polypropylene. Diffuse spots marked ‘E’, ‘P’, and ‘D’ show the reflection from the oxygen layers of olivine in elastic and plastic shock wave regions, and reflection from its denser recrystallised region, respectively. Crystallographic orientations (a and b) are approximately shown for readability, together with the direction of a-axis compression. These axes are not necessarily precisely located on the detector plane. A vertical linear profile within the three orange strips with the Laue indices shows Bragg reflections from the (104), (110), and (113) planes of polycrystalline Al₂O₃. b One dimensional patterns as a function of d obtained by the integration of the images. Positions of the peaks marked with E, P and D show d of their corresponding reflections, d₂₀₀^E, d₂₀₀^P, and d₂₀₀^D, respectively. At t = 4 ns, the d₂₀₀^P was compressed to 94 ± 1 % of d₂₀₀^1atm, which was comparable to the a-axis compression at static pressure of 60 to 100 GPa^57,58. At t = 6 ns, the E and P peaks become much stronger due to the increase in volume of these compressed regions (the shown intensity profile was reduced by a factor of 4). At t = 7 ns, the ‘E’ and ‘P’ peaks moved further to the left to become almost undetectable (see ‘Methods’), while the ‘D’ peak started to grow (d₂₀₀^D = 2.25−2.26 Å, corresponding to d₂₂₂ of ringwoodite at 21 to 25 GPa). At t = 8 ns, the newly-emerged ‘D’ peak rapidly grew; it was also gradually shifting to the right (d₂₀₀^D = 2.25 to 2.31 Å, corresponding to d₂₂₂ of ringwoodite at 6 to 25 GPa). At t = 9 ns, the reflections of Al₂O₃ suddenly became slightly compressed, indicating that the shock wave had travelled throughout the olivine plate to arrive there. The strips with orange (not compressed) and red (compressed) colours are visual guides for the behaviour of these Al₂O₃ peaks.