Evgeny Nazaretski

11 nm hard X-ray focus from a large-aperture multilayer Laue lens

The focusing performance of a multilayer Laue lens (MLL) with 43.4 μm aperture, 4 nm finest zone width and 4.2 mm focal length at 12 keV was characterized with X-rays using ptychography method. The reconstructed probe shows a full-width-at-half-maximum (FWHM) peak size of 11.2 nm. The obtained X-ray wavefront shows excellent agreement with the dynamical calculations, exhibiting aberrations less than 0.3 wave period, which ensures the MLL capable of producing a diffraction-limited focus while offering a sufficient working distance. This achievement opens up opportunities of incorporating a variety of in-situ experiments into ultra high-resolution X-ray microscopy studies.

Pushing the limits: an instrument for hard X-ray imaging below 20 nm

Hard X-ray microscopy is a prominent tool suitable for nanoscale-resolution non-destructive imaging of various materials used in different areas of science and technology. With an ongoing effort to push the 2D/3D imaging resolution down to 10 nm in the hard X-ray regime, both the fabrication of nano-focusing optics and the stability of the microscope using those optics become extremely challenging. In this work a microscopy system designed and constructed to accommodate multilayer Laue lenses as nanofocusing optics is presented. The developed apparatus has been thoroughly characterized in terms of resolution and stability followed by imaging experiments at a synchrotron facility. Drift rates of ∼2 nm h(-1) accompanied by 13 nm × 33 nm imaging resolution at 11.8 keV are reported.

Quantitative x-ray phase imaging at the nanoscale by multilayer Laue lenses

For scanning x-ray microscopy, many attempts have been made to image the phase contrast based on a concept of the beam being deflected by a specimen, the so-called differential phase contrast imaging (DPC). Despite the successful demonstration in a number of representative cases at moderate spatial resolutions, these methods suffer from various limitations that preclude applications of DPC for ultra-high spatial resolution imaging, where the emerging wave field from the focusing optic tends to be significantly more complicated. In this work, we propose a highly robust and generic approach based on a Fourier-shift fitting process and demonstrate quantitative phase imaging of a solid oxide fuel cell (SOFC) anode by multilayer Laue lenses (MLLs). The high sensitivity of the phase to structural and compositional variations makes our technique extremely powerful in correlating the electrode performance with its buried nanoscale interfacial structures that may be invisible to the absorption and fluorescence contrasts.

Multimodality hard-x-ray imaging of a chromosome with nanoscale spatial resolution.

We developed a scanning hard x-ray microscope using a new class of x-ray nano-focusing optic called a multilayer Laue lens and imaged a chromosome with nanoscale spatial resolution. The combination of the hard x-ray’s superior penetration power, high sensitivity to elemental composition, high spatial-resolution and quantitative analysis creates a unique tool with capabilities that other microscopy techniques cannot provide. Using this microscope, we simultaneously obtained absorption-, phase-, and fluorescence-contrast images of Pt-stained human chromosome samples. The high spatial-resolution of the microscope and its multi-modality imaging capabilities enabled us to observe the internal ultra-structures of a thick chromosome without sectioning it.

Fly-scan ptychography

We report an experimental ptychography measurement performed in fly-scan mode. With a visible-light laser source, we demonstrate a 5-fold reduction of data acquisition time. By including multiple mutually incoherent modes into the incident illumination, high quality images were successfully reconstructed from blurry diffraction patterns. This approach significantly increases the throughput of ptychography, especially for three-dimensional applications and the visualization of dynamic systems.

Oxidation of PtNi nanoparticles studied by a scanning X-ray fluorescence microscope with multi-layer Laue lenses

We report a study of the oxidation process of individual PtNi nanoparticles (NPs) conducted with a novel scanning multi-layer Laue lens X-ray microscope. The elemental maps reveal that alloyed PtNi NPs were transformed into Pt/NiO core-shell NPs by thermal oxidation. The observations furthermore indicate that a coalescence of Pt/NiO core-shell NPs occurred during oxidation.

Achieving hard X-ray nanofocusing using a wedged multilayer Laue lens

We report on the fabrication and the characterization of a wedged multilayer Laue lens for x-ray nanofocusing. The lens was fabricated using a sputtering deposition technique, in which a specially designed mask was employed to introduce a thickness gradient in the lateral direction of the multilayer. X-ray characterization shows an efficiency of 27% and a focus size of 26 nm at 14.6 keV, in a good agreement with theoretical calculations. These results indicate that the desired wedging is achieved in the fabricated structure. We anticipate that continuous development on wedged MLLs will advance x-ray nanofocusing optics to new frontiers and enrich capabilities and opportunities for hard X-ray microscopy.

Design and performance of a scanning ptychography microscope

We have designed and constructed a dedicated instrument to perform ptychography measurements and characterization of multilayer Laue lenses nanofocusing optics. The design of the scanning microscope provides stability of components and minimal thermal drifts, requirements for nanometer scale spatial resolution measurements. We performed thorough laboratory characterization of the instrument in terms of resolution and thermal drifts with subsequent measurements at a synchrotron. We have successfully acquired and reconstructed ptychography data yielding 11 nm line focus.

Direct measurement of the magnetic penetration depth by magnetic force microscopy

We present an experimental approach using magnetic force microscopy for measurements of the absolute value of the magnetic penetration depth

Design and performance of an X-ray scanning microscope at the Hard X-ray Nanoprobe beamline of NSLS-II

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