Figure 1
Photographs (a, b) and schematic (c) of the BNP. The BNP is a sample-scanning hard X-ray fluorescence nanoprobe with laser interferometer systems for accurate positioning and cryogenic capabilities dedicated to examination of frozen-hydrated biological samples. The monochromatic X-rays travel in and out of the vacuum chamber through beryllium windows. Fresnel zone plates are used as nanofocusing optics. While the sample is being scanned through the focused beam, fluorescence signals are collected using the detector mounted at 90° with regards to the incident X-ray beam. Downstream of the sample a quadrant photodiode is used to collect transmission signals for differential phase and absorption contrast imaging. The photodiode can also be moved out of the X-ray path to allow the use of either an X-ray transmission camera or a visible-light microscope outside the chamber for alignment. Liquid nitrogen is the primary cooling source. The sample stage, shuttle and robot gripper are conductively cooled by liquid nitrogen during operation.  [article HTML]