Abstract
Spectroscopic full-field transmission X-ray microscopy (TXM-XANES), which offers electrochemical imaging with a spatial resolution of tens of nanometers, is an extensively used unique technique in battery research. However, absorption-based bright-field imaging has poor detection sensitivity for nanoscale applications. Here, to improve the sensitivity, we explored spectroscopic X-ray nano imaging with Zernike phase contrast (ZPC-XANES). A pinhole-type Zernike phase plate, which was optimized for high-contrast images with minimal artifacts, was used in this study. When the absorption is weak, the Zernike phase contrast improves the signal-to-noise ratio and the contrast of images at all energies, which induces the enhancement of the absorption edge step. We estimated that the absorption of the samples should be higher than 2.2% for reliable spectroscopic nano-imaging based on XANES spectroscopy analysis of a custom-made copper wedge sample. We also determined that there is a slight absorption peak shift and sharpening in a small absorption sample due to the inflection point of the refractive index at the absorption edge. Nevertheless, in the case of sub-micron sized cathode materials, we believe that better contrast and higher resolution spectroscopic images can be obtained using ZPC-XANES.
Highlights
Spectroscopic full-field transmission X-ray microscopy (TXM-X-ray absorption near-edge structure (XANES)), which offers electrochemical imaging with a spatial resolution of tens of nanometers, is an extensively used unique technique in battery research
As TXM-XANES is a bright-field microscopy based on the absorption contrast, it has poor detection sensitivity for weakly concentrated materials or thin samples where the absorption is weak compared to the background fluctuations
The Zernike phase contrast (ZPC)-XANES experiment was conducted using the spectroscopic X-ray Nano Imaging Beamline (BL7C) of the Pohang Light Source II (PLS-II, South Korea). This beamline was operated in two modes: zone plate-based full-field transmission X-ray microscopy with Zernike p hase[26,27] and TXM-XANES28
Summary
Spectroscopic full-field transmission X-ray microscopy (TXM-XANES), which offers electrochemical imaging with a spatial resolution of tens of nanometers, is an extensively used unique technique in battery research. To improve the sensitivity, we explored spectroscopic X-ray nano imaging with Zernike phase contrast (ZPC-XANES). As TXM-XANES is a bright-field microscopy based on the absorption contrast, it has poor detection sensitivity for weakly concentrated materials or thin samples where the absorption is weak compared to the background fluctuations. Pinhole-type phase plate, where the zeroth-order frequency focuses on a point and passes through the hole, whereas the phase of the higher-order frequencies shift by π /2 at the phase p late[24,25] Because it focuses on a point and the hole at the phase plate has a diameter of a few μm, we can fix the position of the phase plate at the back focal plane of the absorption edge energy (Supplementary Fig. S1). By scanning the energies across the absorption edge of the sample, we can conduct TXM-XANES with the Zernike phase contrast method (ZPC-XANES), which enhances the sensitivity of the weak absorption sample.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
