Jennifer A. Dionne
VerifiedStanford University · Rheumatology
Active 1996–2026
About
Jennifer A. Dionne is a Senior Associate Vice Provost for Research Platforms/Shared Facilities and an Associate Professor of Materials Science and Engineering at Stanford University. She is also a Senior Fellow at the Precourt Institute for Energy and holds a courtesy appointment as an Associate Professor of Radiology. Her research focuses on the intersection of artificial intelligence in medicine and imaging, contributing to the development of innovative solutions in healthcare through advanced materials and imaging technologies. As a key member of the Center for Artificial Intelligence in Medicine & Imaging (AIMI), she is involved in advancing research, education, and industry collaborations aimed at improving medical diagnostics and treatment.
Research topics
- Nanotechnology
- Materials science
- Physics
- Computer Science
- Optics
- Optoelectronics
- Chemistry
- Chemical physics
- Telecommunications
- Biology
- Crystallography
- Quantum mechanics
- Molecular physics
- Acoustics
- Atomic physics
- Photochemistry
Selected publications
Metasurface-enhanced Momentum-resolved Circular Dichroism Spectroscopy
ChemRxiv · 2026-03-29
articleOpen accessSenior authorNanophotonic resonators can amplify weak molecular circular dichroism (CD) signals, but the structural chirality from angle-dependent photoexcitation or collection may mask intrinsic, molecular chiroptical features. Here, we develop an achiral nanodisk array and angle-resolved spectral measurement approach which deconvolves chiral molecular and substrate signals and enables artifact-free chiral-optical enhancement. Circular polarization-resolved momentum-space spectroscopy maps chiroptical response across wavelength and collection angle in a single measurement, simultaneously reporting intrinsic, molecularly-linked CD and extrinsic, nanostructure-induced signals in distinct optical channels. As a model system, we design silicon nitride nanodisks that overlap spectrally with thiocamphor’s CD features with a simulated ~150 fold, uniform-sign enhancement in the volume-averaged density of optical chirality within the analyte-accessible region. We validate the enhancement of otherwise weak CD signals with the predicted spectral and angular sensitivity in a thiocamphor solution and measure its enantiomeric excesses. Thiocamphor concentrations down to 0.1 mM are detected with robust quantification established at 1 mM, supporting at least one order of magnitude limit of detection improvement relative to a conventional measurement at comparable path length. Additionally, this enhanced CD response demonstrates a monotonically increasing dose–response behavior across enantiomeric excesses ranging from 1% to 25%, consistent with a linear trend across the measured range. Our approach demonstrates momentum-resolved, metasurface-enhanced CD spectroscopy as a promising path to reliable and sensitive detection of molecular chirality and enantiomeric purity.
arXiv (Cornell University) · 2026-01-31
articleOpen accessSenior authorBimetallic catalysts provide new routes toward sustainable ammonia synthesis, but the structural dynamics controlling their performance under real-world conditions remain poorly understood. Here, we combine in situ gas-cell and multimodal electron microscopy to disentangle the temperature-, pressure-, and chemistry-dependent restructuring of AuRu catalysts, revealing pathways accessible only at atmospheric pressure. As synthesized, AuRu nanocatalysts are polycrystalline face-centered-cubic alloys with Au/Ru intermixing that phase-segregate into Au- and Ru-rich domains with elevated temperature (>450 °C). Increased pressure (~1 atm in 3:1, hydrogen:nitrogen) unlocks pronounced faceting and internal nanovoid formation, which systematic gas-chemistry variation identifies as hydrogen-driven. Density functional theory-based interatomic potentials show that hydrogen can amplify Au/Ru diffusion asymmetry, promoting nanovoid formation via a gas-mediated Kirkendall mechanism. Together, these results bridge the pressure gap between traditional in situ electron microscopy and benchtop ammonia reactors, enabling resolution of distinct restructuring stimuli in multicomponent systems.
Enhanced enantiomer discrimination with chiral surface plasmons
arXiv (Cornell University) · 2026-04-06
preprintOpen accessStrong light-matter coupling in chiral cavities has been proposed as an effective way to selectively interact with an enantiomer that shares the same handedness as the cavity's chiral mode. We show that surface plasmons supported by a two-dimensional interface with both electric and chiral conductivities discriminate enantiomers more efficiently than chiral optical cavities. A quantum-electrodynamic treatment is developed to incorporate the molecule's electric and magnetic dipole moments. We show that the discrimination factor for a chiral plasmon can exceed that of the best chiral-mirror cavity by almost an order of magnitude due to stronger field confinement. In addition, surface plasmons couple to a dipole's projection onto an entire plane, whereas cavity (or free-space) modes couple only to a single polarization axis. This geometric difference produces a $\sqrt{2}$ orientation-averaged boost in chiral discrimination for chiral surface platforms. A handedness-preserving reflector further amplifies the enhancement, opening a practical route towards chiral sensing using twisted-layer platforms.
$Q$ Factors Exceeding $10^{4}$ in Wavelength-to-Subwavelength-Scale Free-Space Resonators
arXiv (Cornell University) · 2026-04-06
articleOpen accessSenior authorFree-space-addressable optical resonators that combine long photon lifetimes (high $Q$ factors) with strong spatial localization of optical fields (small mode volumes, $V_m$) enhance light-matter interactions with facile far-field excitation. The Purcell factor governing spontaneous emission enhancement scales as $Q\,V_m^{-1}$. Periodically asymmetric resonators, in which perturbations convert bound modes into radiating modes, offer a route to free-space resonances, with the radiative $Q$ factor tuned by the geometric and optical strength of the asymmetry-inducing perturbations. However, free-space resonators that simultaneously achieve high $Q$ and small $V_m$ have remained rare. This limitation arises in part because existing designs do not tailor geometric and optical asymmetries concurrently, thus limiting access to high-$Q$ regimes. Here, we show that jointly tuning geometric and optical asymmetries unlocks a biaxial radiative landscape with iso-$Q$ contours that connect disparate perturbations with equivalent $Q$ factors. We demonstrate this framework with very-large-scale-integrated single-crystalline Si nanoantenna pixels (VINPix) with out-of-plane perturbations of 35-150 nm amorphous Si, SiN$_x$, and SiO$_2$. We experimentally establish biaxial $Q$ factor control in air and achieve $Q$ factors up to $76,000$ at wavelength-scale mode volumes ($V_m \sim 1.7\,λ_0^3\,n_{\mathrm{eff}}^{-3}$) in simultaneously imaged arrays of $>80$ resonators in water. Furthermore, we computationally demonstrate 50-nm-wide slotted VINPix that reach $Q$ factors of $10^6$ at subwavelength mode volumes ($V_m \sim 0.2\,λ_0^3\,n_{\mathrm{eff}}^{-3}$) with 20 nm SiO$_2$ perturbations, yielding Purcell factors as high as $5 \times 10^5$ in an all-dielectric free-space resonator.
Nano Letters · 2026-02-18
articleTwisted epitaxy enables precise orientation control of nanostructures confined within van der Waals (vdW) gaps. Here, we investigate the moiré and electronic structure of a representative twisted epitaxial system, where Au nanodiscs are grown inside twisted bilayer MoS2 with a 6° interlayer twist, inducing a 3° symmetrical misalignment of Au relative to each MoS2 layer (MoS2–Au–MoS2). Using multislice electron ptychography (MEP), we resolve the three-dimensional “moiré-of-moirés” structure of MoS2–Au–MoS2 with atomic resolution. Electron energy loss spectroscopy (EELS) shows that MoS2 encapsulation significantly reduces the plasmon energy of Au nanodiscs compared with their unencapsulated counterparts. Furthermore, first-principles calculations reveal that Au insertion alters the electronic band alignment near the Fermi level of bilayer MoS2. Our results introduce a twisted MoS2–Au–MoS2 heterostructure as a structurally and electronically rich material system and establish twisted epitaxy as a new strategy for moiré engineering and the synthesis of 2D-confined materials with tunable optoelectronic properties.
arXiv (Cornell University) · 2026-04-09
articleOpen accessSenior authorRadioluminescent nanostructures provide a pathway to the fabrication of next-generation scintillators with tunability in composition, size, and morphology, and spectral and temporal properties, as well as scalable processing. Here we create a 3D millimeter-scale solid-state scintillators from SrLuF Ce3+, Pr3+ (SrLuF) core-shell nanostructures, integrating nanoscale building blocks into self-assembled macroscopic crystals. These scintillators exhibit single-digit nanosecond decay times, linear response, resistance to radiation-induced degradation, and optical emission yields within an order of magnitude of YAG Ce3+. We select a SrLuF host lattice owing to its high effective atomic number, wide band gap, and low phonon energy, which together support efficient 4f-5d radiative transitions from Ce3+ and Pr3+ activators while suppressing afterglow. We create a library of core-shell nanoscintillators with undoped SrLuF shells and cores spanning compositions from undoped SrLuF to fully doped SrCeF or SrPrF. Time-resolved and steady-state X-ray excited optical luminescence (XEOL) reveal broadband emission at 310 nm (Ce3+) and 335 nm (Pr3+) with biexponential decays in the sub-nanosecond (100-500 ps) and sub-15 ns (4-13 ns) regimes, demonstrating tunable radiative efficiency and ultrafast dynamics. Ensemble performance of the mm-scale superlattices is characterized under both continuous-wave and femtosecond high-intensity excitation, revealing high light yield, linear response, and radiation hardness under extreme irradiation of ultrafast 50fs X-ray pulses up to 5mJ per mm2 corresponding to a peak intensity of 1013 W per cm2. Together, these results establish a design framework for stable, bright, and tunable scintillation platforms with applications in precision health, space exploration and hard X-ray imaging at next-generation free-electron laser facilities.
Dynamic, single-cell monitoring of CAR T cell identity and activation with Raman spectroscopy
bioRxiv (Cold Spring Harbor Laboratory) · 2026-02-23
articleOpen accessSenior authorCorrespondingChimeric antigen receptor (CAR) T cell therapies have reshaped treatment for cancers and immune-mediated diseases, yet their safety and efficacy depend on both the proliferation of engineered cells and their dynamic functional state - features that remain challenging to monitor in real-time clinical settings. Current methods require labels, extensive processing, and provide only static snapshots of cell identity and activation. Here, we introduce a surface-enhanced Raman spectroscopy and machine learning approach that enables label-free single-cell identification of engineered CAR T cells and time-resolved, semi-continuous monitoring of their functional activation state. Using the intrinsic vibrational signatures from live cells, we detect spectral differences resulting from engineered receptor expression in donor-derived CD19- and GD2-targeted CAR T cells (nine and five donors, respectively) with 81-85% donor-level accuracy and resolve dynamic antigen-specific activation trajectories with temporal precision. These capabilities stem from biochemical signatures consistent with processes such as receptor expression, tonic signalling, and immune synapse formation, demonstrating a single method that reports both cellular identity and activation state with biochemical specificity. Our results extend CAR T cell monitoring beyond static phenotyping and establish the potential of SERS-ML analysis for rapid, point-of-care assessment of engineered immune cells.
arXiv (Cornell University) · 2026-01-24
preprintOpen accessFour-dimensional scanning transmission electron microscopy (4D-STEM) enables mapping of diffraction information with nanometer-scale spatial resolution, offering detailed insight into local structure, orientation, and strain. However, as data dimensionality and sampling density increase, particularly for in situ scanning diffraction experiments (5D-STEM), robust segmentation of structurally consistent behavior across sequential measurements becomes essential for efficient and physically meaningful analysis. Here, we introduce a clustering framework that identifies crystallographically distinct domains from 4D-STEM datasets. By using local diffraction-pattern similarity as a metric, the method extracts closed contours delineating spatially contiguous regions. This approach produces cluster-averaged diffraction patterns that improve signal quality while reducing data volume by orders of magnitude, enabling rapid and accurate orientation, phase, and strain mapping. We demonstrate the applicability of this approach to in situ liquid-cell 4D-STEM data of gold nanoparticle growth. Our method provides a scalable and generalizable route for spatially coherent segmentation, data compression, and quantitative structure-strain mapping across diverse 4D-STEM modalities. The full analysis code and example workflows are publicly available to support reproducibility and reuse.
arXiv (Cornell University) · 2026-04-20
preprintOpen accessSenior authorMethane (CH4) and nitrous oxide (N2O) are potent greenhouse gases that represent substantial chemical energy. Conversion of these abundant waste gases to high-value chemicals typically requires high temperatures up to 1000 C, producing substantial CO2 emissions and limited selectivity toward desirable multi-carbon products. Here we demonstrate a plasmonic photocatalyst that enables CH4 and N2O conversion under ambient conditions to form C2 and C3 hydrocarbons. By systematically tuning AuPd alloys on TiO2, we identify an optimal composition (AuPd0.05) where Au enhances light harvesting and Pd enables selective C-H activation and C-C coupling. Under visible-light illumination, this catalyst produces C2H4, C2H6, C3H6, and C3H8 with ~80% selectivity while suppressing CO2 formation. In-situ spectroscopy and hot-carrier calculations show that plasmon-generated carriers redistribute interfacial hydroxyl intermediates, shifting the hydrophilic center to suppress overoxidation. Ab-initio calculations further reveal the reduction in C-C coupling barriers from 2.7 eV to 0.7 eV under illumination. Our work illustrates how engineering interfacial electronic and adsorbate dynamics enables selective multicarbon formation.
ArXiv.org · 2026-04-20
articleOpen accessSenior authorMethane (CH4) and nitrous oxide (N2O) are potent greenhouse gases that represent substantial chemical energy. Conversion of these abundant waste gases to high-value chemicals typically requires high temperatures up to 1000 C, producing substantial CO2 emissions and limited selectivity toward desirable multi-carbon products. Here we demonstrate a plasmonic photocatalyst that enables CH4 and N2O conversion under ambient conditions to form C2 and C3 hydrocarbons. By systematically tuning AuPd alloys on TiO2, we identify an optimal composition (AuPd0.05) where Au enhances light harvesting and Pd enables selective C-H activation and C-C coupling. Under visible-light illumination, this catalyst produces C2H4, C2H6, C3H6, and C3H8 with ~80% selectivity while suppressing CO2 formation. In-situ spectroscopy and hot-carrier calculations show that plasmon-generated carriers redistribute interfacial hydroxyl intermediates, shifting the hydrophilic center to suppress overoxidation. Ab-initio calculations further reveal the reduction in C-C coupling barriers from 2.7 eV to 0.7 eV under illumination. Our work illustrates how engineering interfacial electronic and adsorbate dynamics enables selective multicarbon formation.
Recent grants
Enhancing helicity-dependent optical interactions in inversion-asymmetric materials
NSF · $450k · 2019–2022
CAREER: Symmetry Breaking in Metamaterials: Giving a "Twist" to Light-Matter Interactions
NSF · $623k · 2012–2018
NIH · $236k · 2018–2022
Nano-optical reporters of dynamic mechanotransduction in the immune system
NIH · $2.3M · 2019–2024
NSF · $1.0M · 2019–2025
Frequent coauthors
- 38 shared
Aitzol García‐Etxarri
Donostia International Physics Center
- 34 shared
Mark Lawrence
- 33 shared
Harry A. Atwater
California Institute of Technology
- 30 shared
A. Paul Alivisatos
University of Chicago
- 26 shared
Amr A. E. Saleh
Cairo University
- 26 shared
Hadiseh Alaeian
- 23 shared
Jack Hu
- 20 shared
Stefan Fischer
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