SONDERSEMINAR: X-ray Nanofocus Imaging by Second-Order Correlation of X-ray Fluorescence

Coherent diffraction imaging (CDI) with X-ray free-electron lasers (XFELs) combines high spatial and temporal resolutions. However, CDI is limited to imaging a 2D projection of the studied sample for a specific sample orientation, as it relies on coherent scattered radiation for imaging. Therefore, diffraction patterns must be recorded for a large number of sample orientations to obtain 3D information about the sample in question.

We present an alternative approach for imaging with XFELs. Incoherent diffractive imaging (IDI), originally proposed by Classen et al. (2017), is based on intensity correlations of incoherently emitted X-ray fluorescence radiation instead of coherently scattered radiation. The intensity correlation of incoherent radiation allows IDI to scan a 3D region of the phase space of the imaged samples, requiring fewer different sample orientations for 3D reconstruction than CDI using comparable experimental setups.

In this talk, we will present recent experimental IDI data recorded using sub-femtosecond FEL pulses available at SLAC/LCLS from thin metal samples. We reproduce the results of Nakamura et al. (2020), who demonstrated how IDI can be utilized for XFEL nanofocus characterization, and we present evidence that hints at the 3D structure determination capabilities of IDI.

Classen et al., Phys. Rev. Lett. 119, 053401 (2017)
Nakamura et al., J. Synchrotron Rad. 27, 1366-1371 (2020)