Lauren Mason – STROBE

Congratulations to Aleksandr Smirnov for Receiving a 2026 Kavli Energy NanoScience Institute Graduate Fellowship

Aleksandr Smirnov is a 3rd year Ph.D. candidate in Chemistry working in Naomi Ginsberg’s group. Before coming to UC Berkeley, Smirnov received a B.A. with high honors in Chemistry from Kenyon College, where he correlated changes in vibrational spectra of perylene and naphthalene diimide thin films to investigate their coupling and charge transfer interactions.

Aleksandr’s doctoral work focuses on understanding and controlling hierarchical material formation through the development of a novel benchtop microscope to facilitate efficient material design and discovery. Specifically, Smirnov has used interferometric scattering microscopy (iSCAT) to size evolving nanoparticles in solution below the diffraction limit with minimal perturbation to the reaction.

As a Kavli ENSI fellow, Aleksandr is applying iSCAT to gain insight into the self-assembly of metal-organic frameworks (MOFs). Though this class of porous materials holds great promise in gas capture, catalysis, and drug delivery, MOF formation remains poorly understood, limiting material design. Aleksandr aims to utilize iSCAT to extract time-dependent physical and hydrodynamic size, polydispersity, diffusion constant, and refractive index for varied reaction conditions, which will guide him towards optimizing them to improve crystallinity, monodispersity, and yield. The broader correlations between in situ measurements and reactant identities help classify reactions based on their evolution and complexity, providing insight into the principles of hierarchical material formation.

Congratulations to John Davis for Receiving a 2026 Kavli Energy NanoScience Institute Graduate Fellowship

John Patrick Davis (JD) is a third-year Ph.D. student in Chemistry at UC Berkeley, advised by Professor Naomi Ginsberg. He earned an M.S. in Chemistry from the College of William and Mary, where he studied atmospheric reaction complexes using gas-phase laser spectroscopy, and a B.S. in Chemistry from Washington and Lee University, focusing on computational modeling and hyperspectral imaging.

JD’s doctoral research focuses on controlling the self-assembly of colloidal semiconductor nanocrystals. A spectroscopist by training, he leverages coherent X-ray scattering to capture microscopic fluctuations as components configure and rearrange, ultimately aiming to establish predictive frameworks for next-generation material design.

As a Kavli ENSI fellow, JD will focus on building a microscopic understanding of how components move and organize within solid-state electrolytes (SSEs) and nanocrystal assemblies. While these materials hold immense promise for next-generation energy storage and optoelectronics, researchers remain fundamentally limited by an inability to directly track their dynamics across vastly different scales of time and space. Building on his previous work, where he used advanced X-ray scattering techniques to reveal how nanocrystals navigate chaotic, disordered phases to form ordered crystal structures, JD plans to bridge the gap between atomic-scale motion and macroscopic performance. By combining these multiscale X-ray tracking methods with advanced computer modeling, he aims to uncover the fundamental design principles governing these systems, providing the predictive insights essential for engineering next-generation energy storage, conversion, and separation technologies.

Congratulations to José L. Godínez Castellanos for Being a 2025-2026 Chancellor’s Postdoctoral Fellow in the Department of Chemistry at UC Berkeley

José L. Godínez Castellanos is a 2025-2026 Chancellor’s Postdoctoral Fellow in the Department of Chemistry working with Professor. Naomi S. Ginsberg. José’s current work revolves around understanding charge carrier and thermal transport, and their interconversion in solid state doped silver selenide thermoelectrics. He uses stroboscopic interferometric scattering to provide a spatially- and time-resolved perspective of energy transport in these materials. This approach offers a new framework where we probe a material’s intrinsic properties and the effect of mesoscale structure in thermal transport—helping chemists understand the effects of dopants and design high-efficiency thermoelectrics.

José’s PhD work explored different structural effects (e.g., sequence, conformers, chromatin region location) that modulate the ultrafast formation of cyclobutane pyrimidine dimers in DNA after absorption of UV light. José received a PhD in Physical Chemistry from the University of Southern California, and a B.S. in Chemistry from the California State University, Stanislaus.

Congratulations to Naomi Ginsberg for Receiving the 2026 Brown Investigator Award

Congratulations for Naomi Ginsberg for receiving the 2026 Brown Investigator Award to study and optimize the assembly of complex functional materials by tracking and adaptively steering the formation processes in real time.

The Brown Institute for Basic Sciences at Caltech announced the 2026 class of Brown Investigators on May 18, 2026. The cohort, the third to be selected through the Brown Institute for Basic Sciences, comprises eight distinguished mid-career faculty working on fundamental challenges in the physical sciences, particularly those with potential long-term practical applications in chemistry and physics. Each investigator will receive up to $2 million over five years.

Brown established the Investigator Awards in 2020 through the Brown Science Foundation in support of the belief that scientific discovery is a driving force in the improvement of the human condition. The Brown Institute for Basic Sciences at Caltech seeks to advance fundamental science discoveries with the potential to seed breakthroughs that benefit society.

High-Resolution Broadband Ptychography with a Tabletop EUV Continuum

Ptychography implemented with coherent high-harmonic (HHG) sources enables high-resolution, high-fidelity imaging of nanostructures and biosystems. However, when driven by mid-infrared lasers to generate light at higher photon energies, HHG inherently produces a broadband quasi-continuum, which is less suited for coherent imaging compared with a single harmonic order. Consequently, experiments typically select a narrow bandwidth of ≈1%, leaving most of the HHG photons unused, increasing exposure times. In this work, we demonstrate broadband ptychography utilizing an extreme UV (EUV) continuum centered at 92 eV, with a bandwidth of up to 7.9 eV (a relative bandwidth of ~9%). By focusing the HHG beam to a sub-micrometer spot size to relax the temporal coherence constraints, and utilizing a multi-wavelength ptychographic reconstruction algorithm, we achieve a spatial resolution of 42 nm, which is near the diffraction limit of ~30 nm for our setup. To the best of our knowledge, this represents the broadest spectral bandwidth successfully employed to date for EUV ptychography, with the potential to increase the usable photon flux by up to an order of magnitude relative to previous approaches. In the future, broadband soft X-ray ptychography can be used to image hydrated samples around the carbon K-edge and magnetic textures at the L-edges of transition metals.

Imaging the functioning of FeFETs

Ferroelectric materials such as hafnium zirconium oxide (HZO) are likely to form the basis of a next-generation memory technology. For instance, replacing the conventional gate dielectric in a field-effect transistor (FET) with HZO can form a ferroelectric FET, or FeFET. Chris Regan’s group at UCLA has been working with Suman Datta’s group at Georgia Tech to speed development of this exciting technology. Standard scanning transmission electron microscopy (STEM) (see top left figure), shows the basic layout of a device fabricated at Georgia Tech, but it reveals little about its function. STEM electron-beam induced current (EBIC) imaging at UCLA, on the other hand, shows exactly how the FeFET works. With two EBIC transimpedance amplifiers (Fig. X, top right), the STROBE team can form two linear combinations. The STEM EBIC sum image (see lower left figure), gives secondary-electron EBIC (SEEBIC) contrast. It maps the conductors, correctly showing that the electrode in the upper left corner is not connected to the gate, source, or drain. The STEM EBIC difference image (see lower right figure) gives electron-hole-pair separation contrast, and it is even more informative. It reveals the electric fields that control the FeFET’s function: the depolarization fields in the ferroelectric HZO where the gate electrode overlaps the semiconducting indium tungsten oxide (IWO). Moreover, it reveals these fields just as well whether it has to image through 40 nm of palladium or not. Higher magnification images of the FeFET in both polarization states (not shown) show exactly how much of the ferroelectric switches, providing a structural explanation of the FeFET threshold voltages and memory window. This functional imaging technique – STEM EBIC imaging – is a unique and uniquely powerful development enabled by STROBE.

Trypanosome doublet microtubule structures reveal flagellum assembly and motility mechanisms

Integrated cryogenic electron microscopy (cryoEM) and cryogenic electron tomography (cryoET) approach, advanced through NSF’s STROBE, a National Science Foundation Science and Technology Center, enables unparalleled resolution for complex cellular structures like the flagellar doublet microtubules (DMT) of Trypanosoma brucei. This parasite causes African sleeping sickness, affecting millions. The flagellum is essential for motility, infectivity, and survival across different host environments. STROBE-supported cryoEM at the EICN resource at UCLA allowed high-resolution imaging of native structures, bypassing artifacts of recombinant systems and revealing detailed architecture of the 96-nm repeat with 154 proteins, including 40 parasite-specific ones (see figure).

The study provides critical insights into motility mechanisms by capturing axonemal dynein motors in the pre-power stroke conformation. This supports a novel ‘dragon boat’ model in which coordinated power strokes of dyneins drive microtubule sliding, generating the characteristic helical waveform that powers parasite movement through blood and tissues. Significantly, dyneins are the molecular motor across all living cells, including ours, and the mechanisms are universal.

This STROBE-supported, NSF-funded cryoEM study elucidates the mechanochemical basis of flagellar motility, offering new avenues for therapeutic intervention against trypanosomatid diseases and advancing our understanding of eukaryotic flagella evolution and function.

Designing lensless imaging systems to maximize information capture

Lensless imagers can make cameras far thinner than conventional optics and can compress rich scene information into a single measurement. But the same optical multiplexing that enables those advantages can also scramble a scene so strongly that reconstruction loses the information it needs. We address this design problem by evaluating lensless encoders through mutual information estimated directly from noisy measurements. By combining a probabilistic model of measurement distributions with a detector-noise model, we compare encoders without tying performance to any one reconstruction algorithm and quantify how object sparsity, encoder multiplexing, and noise interact. Across simulations, we show that dense objects are best matched to low-multiplexing encoders, whereas progressively sparser objects benefit from higher multiplexing. We then optimize phase-mask encoders for specific object classes, and these information-optimal designs outperform heuristic masks in mutual information while also improving downstream reconstruction quality. Experiments with a conventional lens, a random multi-focal lenslet array, and a diffuser reinforce the same lesson for dense natural images: more multiplexing can reduce recoverable information. By making information capture itself the design target, our work offers decoder-independent engineering rules for lensless imaging and other multiplexed computational imaging systems. Because the best encoder depends on the assumed object distribution and mutual information does not guarantee every task-specific outcome, the next step is to test robustness under distribution shift, alternate noise models, and specialized downstream tasks.

Multimodal Nanoscale Mapping of Local Structure and CO2 Adsorption in Metal–Organic Frameworks

Currently, host-guest interactions in metal–organic frameworks (MOFs) are mainly understood via theoretical simulations, bulk characterization techniques, and x-ray diffraction, all of which can average out information related to defects, interfaces, and spatial heterogeneity among adsorption sites. Since these structural features can directly impact the functionality of MOFs we applied local probes to investigate these effects. Specifically, we applied both 3D electron diffraction and 4D scanning transmission electron microscopy to structurally characterize and spatially visualize the effect of gas-loading and diamine functionalization in MOF crystals. In addition, complementary infrared scattering scanning near-field optical microscopy measurements confirmed spatial variations of chemisorbed CO₂ inside an individual crystal.

The results of our multimodal approach was the ability to map heterogeneity arising from host-guest interactions and material functionalization. Our 3D electron diffraction data has provided the only ab initio electrostatic potential map of any variant of Mg₂(dobpdc), which has been an elusive structure. Our 4D-STEM images are, to our knowledge, the only dual-space (i.e., real and reciprocal space) visualizations of a MOF. Most importantly, although we have applied this methodology to a specific material of interest in gas storage and separation, we hope to introduce these microscopy techniques to the community as effective tools, complementary to the established bulk techniques, by which to evaluate and optimize synthetic and post-synthetic modification procedures of MOFs.

Accurate determination of the 3D atomic structure of amorphous materials

Amorphous materials — solids lacking long-range periodic order — are vital to technologies spanning thin-film electronics, solar cells, phase-change memory, magnetic components, biomedical devices, and quantum hardware. Yet their structural disorder has long prevented full three-dimensional (3D) atomic mapping. Despite major advances in probing short- and medium-range order, experimentally determining complete 3D atomic arrangements in amorphous solids remains challenging. Atomic electron tomography (AET) now offers a route to direct 3D atomic imaging without requiring crystallinity or averaging. In a forthcoming Nature paper, Miao and collaborators present a quantitative analysis of AET, showing how coordinated preprocessing, denoising, projection alignment, normalization, tomographic reconstruction, atom tracing, elemental classification, and atomic position refinement enable reliable 3D atomic coordinate and chemical-identity determination in amorphous materials. Using multislice-simulated datasets, they demonstrate accurate 3D reconstruction of amorphous Si, SiGeSn, and CoPdPt nanoparticles with picometer-scale precision across a range of noise levels. In the CoPdPt system, for example, 95.1 percent of Co, 99.0 percent of Pd, and 100 percent of Pt atoms are correctly identified with 3D positional precisions of 29, 12, and 6 pm. These results establish practical guidelines and quantitative benchmarks for accurate AET of non-crystalline materials, and the underlying workflow provides a general framework for high-fidelity 3D reconstruction in other tomographic imaging modalities.

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About Lauren Mason