Continuous scanning for Bragg coherent x-ray imaging We explore the use of continuous scanning Here, we demonstrate continuous scanning BCDI on a selected during data acquisition for Bragg coherent Pt nanoparticle. We compare the BCDI measurement and reconstruction of the shape and strain fields of the particle diffraction imaging. The fidelity of measured by the two techniques. continuous scanning Bragg coherent diffraction imaging is demonstrated on a RESULTS single Pt nanoparticle in a flow reactor at Figure 1 displays the sum of all the detector images acquired in 400°C. We show a reduction of 30% in total the vicinity of the 111 Pt reflection for the same Pt particle and for scan time compared to conventional step- both methods (step-by-step and continuous scanning). The two patterns are very similar. The continuous scan was executed in by-step scanning. The reconstructed Bragg 6 min 42 s compared to the step-by-step scan, which lasted 9 electron density, phase, displacement and min 24 s. The overall time was then significantly reduced with a strain fields are in excellent agreement with 30% gain, improving the reliability of data acquisition by limiting the time available for sample drift. the results obtained from conventional step- by-step scanning. Continuous scanning will FIGURE 1 allow to minimise sample instability under the beam and will become increasingly important at diffraction-limited storage ring light sources. Coherent diffraction imaging (CDI) is a lensless imaging technique [1]. It allows one to reconstruct isolated two- or three-dimensional objects from their measured diffraction pattern using computational inversion algorithms. The technique has been successfully applied in the Bragg geometry to recover the displacement and strain fields within finite crystals [2]. In Bragg CDI (BCDI), one records the 3D intensity distribution around a Bragg peak by varying the incident angle or the sample azimuth of the x-ray beam with respect to the sample on the order of a few degrees (for instance, /home/webapps/asp_fr/data/asp/publications/synchrotron-soleil/synchrotron-soleil-2020/soleil-highlights-2020-hd-ss-tc±1°). However, its The Bragg electron density and the phase were reconstructed nature as a scanning technique poses strict requirements on from both diffraction patterns in the crystal frame. In Bragg the instrumentation. Typically, step-by-step scanning is used to geometry, the retrieved image is a complex field encoding the record the 3D intensity. It has the drawback that the movement electronic density (in its modulus) and the displacement field of the motor(s) and the acquisition are done in separate steps. u(r) projected onto the scattering vector (in its phase). As the͢͢ In contrast, continuous scanning eliminates the overhead of the 111 Pt reflection has been measured, the retrieved displacement step-by-step scan. There have been examples of continuous field is u . The strain component is then derived from the scanning on extended samples in the field of ptychography, retrieved displacement field: e111 = δu /δy' , where y' is along where the sample is spatially scanned with a focused coherent the 111 direction. Figure 2 displays different 3D views of the111 111 x-ray beam impinging upon it. But, no demonstration has been BCDI reconstruction of the strain field along the [111 ] direction, performed for BCDI on single objects. This method is particularly , for both scanning methods. The reconstructed shape of the attractive for operando measurements soon to be realised at e111 almost diffraction-limited x-ray sources. Pt crystal is a well faceted particle and the particle size is /home/webapps/asp_fr/data/asp/publications/synchrotron-soleil/synchrotron-soleil-2020/soleil-highlights-2020-hd-ss-tc615 90