Publications by authors named "K Ayyer"
Article Synopsis
- Nanoparticles with varied structures are a major focus in research, and new techniques like high-throughput single-particle imaging (SPI) with X-ray free-electron lasers (XFELs) are now enabling the analysis of millions of these particles.
- To effectively utilize this technology, researchers faced three key challenges: understanding structural variability, extracting relevant parameters from measurements, and comparing multiple structural models to the data collected.
- By addressing these challenges, scientists mapped the diverse shapes of gold nanoparticles, revealing important insights into their asymmetry, stable shape patterns, and how external factors like surfactants influence their structure, making nanoparticle characterization more reliable.
This paper introduces spectral incoherent diffractive imaging (SIDI) as a novel method for achieving dark-field imaging of nanostructures with heterogeneous oxidation states. With SIDI, shifts in photoemission profiles can be spatially resolved, enabling the independent imaging of the underlying emitter distributions contributing to each spectral line. In the x-ray domain, this approach offers unique insights beyond the conventional combination of diffraction and x-ray emission spectroscopy.
View Article and Find Full Text PDFThe idea of using ultrashort X-ray pulses to obtain images of single proteins frozen in time has fascinated and inspired many. It was one of the arguments for building X-ray free-electron lasers. According to theory, the extremely intense pulses provide sufficient signal to dispense with using crystals as an amplifier, and the ultrashort pulse duration permits capturing the diffraction data before the sample inevitably explodes.
View Article and Find Full Text PDFFree-electron lasers (FEL) are revolutionizing X-ray-based structural biology methods. While protein crystallography is already routinely performed at FELs, Small Angle X-ray Scattering (SAXS) studies of biological macromolecules are not as prevalent. SAXS allows the study of the shape and overall structure of proteins and nucleic acids in solution, in a quasi-native environment.
View Article and Find Full Text PDFSecond-order intensity correlations from incoherent emitters can reveal the Fourier transform modulus of their spatial distribution, but retrieving the phase to enable completely general Fourier inversion to real space remains challenging. Phase retrieval via the third-order intensity correlations has relied on special emitter configurations which simplified an unaddressed sign problem in the computation. Without a complete treatment of this sign problem, the general case of retrieving the Fourier phase from a truly arbitrary configuration of emitters is not possible.
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