Fig. 1
Sketch of the stroboscopic Scanning X-ray Diffraction Microscopy (s-SXDM) experimental geometry. a Periodic bunch patterns of the Advanced Photon Source (APS) synchrotron are frequency matched to RF continuous wave excitation of a SAW (illustrated in red). Stroboscopic illumination allows for nanoscale SXDM of a virtually frozen wave. b The time domain surface displacement of the SAW (red curve–1 nm peak-to-peak displacement at 352 MHz) is synchronized to the time structure of the X-ray illumination (blue curve– 22 ps rms width at approximately 88 MHz). This allows a flexible measurement of the SAW amplitude by varying either time (detuned near-frequency match) or RF phase (at frequency match) to relatively displace the measurement to a new time slice (dotted blue line). c The out-of-plane displacement of the SAW at a fixed point in time is represented by the orange isosurface, exhibiting both periodic lattice curvature along the wave longitudinal propagation direction y (green dots) and transverse curvature along x (magenta dots) induced by Gaussian focusing of the standing wave. These curvatures induce orthogonal shifts in the far field diffraction pattern that oscillate as a function of the relative phase between the synchrotron time structure and the RF SAW excitation. The two lobe feature of the nanodiffraction patterns is a consequence of the beam stop for the X-ray focusing optic (not shown)
