A5014624803- Material Dynamics and Properties
- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- Theoretical and Computational Physics
- Quantum and electron transport phenomena
- Quantum, superfluid, helium dynamics
- Physics of Superconductivity and Magnetism
- 2D Materials and Applications
- Perovskite Materials and Applications
- Glass properties and applications
- Molecular Junctions and Nanostructures
- Quantum many-body systems
- Strong Light-Matter Interactions
- Cold Atom Physics and Bose-Einstein Condensates
- Graphene research and applications
- Advanced Thermodynamics and Statistical Mechanics
- Liquid Crystal Research Advancements
- Machine Learning in Materials Science
- Photochemistry and Electron Transfer Studies
- Phase Equilibria and Thermodynamics
- Quantum Information and Cryptography
- Catalysis and Oxidation Reactions
- Catalytic Processes in Materials Science
- Chalcogenide Semiconductor Thin Films
- Organic Electronics and Photovoltaics
Columbia University
2016-2025
Flatiron Health (United States)
2020-2021
Flatiron Institute
2020-2021
William & Mary
2017-2021
Williams (United States)
2017-2021
University of California, Berkeley
2021
Schrodinger (United States)
2020
Lawrence Livermore National Laboratory
2020
Tel Aviv University
2002-2017
CEA Paris-Saclay
2013
We have experimentally determined the energies of ground and first four excited excitonic states fundamental optical transition in monolayer WS2, a model system for growing class atomically thin two-dimensional semiconductor crystals. From spectra, we establish large exciton binding energy 0.32 eV pronounced deviation from usual hydrogenic Rydberg series levels states. explain both these results using microscopic theory which non-local nature effective dielectric screening modifies...
We present a microscopic theory of neutral excitons and charged (trions) in monolayers transition metal dichalcogenides, including molybdenum disulfide. Our is based on an effective mass model trions, parametrized by ab initio calculations incorporating proper treatment screening two dimensions. The calculated exciton binding energies are good agreement with high-level many-body computations the Bethe-Salpeter equation. Furthermore, our for more complex trion species compare very favorably...
In monolayer graphene, substitutional doping during growth can be used to alter its electronic properties. We scanning tunneling microscopy (STM), Raman spectroscopy, x-ray and first principles calculations characterize individual nitrogen dopants in graphene grown on a copper substrate. Individual atoms were incorporated as graphitic dopants, fraction of the extra electron each atom was delocalized into lattice. The structure nitrogen-doped strongly modified only within few lattice spacings...
Abstract The ability to control the size of electronic bandgap is an integral part solid-state technology. Atomically thin two-dimensional crystals offer a new approach for tuning energies states based on unusual strength Coulomb interaction in these materials and its environmental sensitivity. Here, we show that by engineering surrounding dielectric environment, one can tune exciton binding energy monolayers WS 2 WSe hundreds meV. We exploit this behaviour present in-plane heterostructure...
We study the thermal motion of colloidal tracer particles in entangled actin filament (F-actin) networks, where particle radius is comparable to mesh size F-actin network. In this regime, ensemble-averaged mean-squared displacement proportional ${\ensuremath{\tau}}^{\ensuremath{\gamma}}$, $0<\ensuremath{\gamma}<1$ from $0.1<\ensuremath{\tau}<100\text{ }\mathrm{s}$ and depends only on ratio probe size. By directly imaging hundreds over 20 min, we determine anomalous subdiffusion due dynamics...
Robust methods to tune the unique electronic properties of graphene by chemical modification are in great demand due potential two dimensional material impact a range device applications. Here we show that carbon and nitrogen core-level resonant X-ray spectroscopy is sensitive probe bonding structure dopants introduced single-sheet films. In conjunction with density functional theory based calculations, able obtain detailed picture bond types doped at sub-percent level. We different N-bond...
We have identified excited exciton states in monolayers of MoS2 and WS2 supported on fused silica by means photoluminescence excitation spectroscopy. In monolayer WS2, the positions A imply an binding energy 0.32 eV. MoS2, transitions are observed at energies 2.24 2.34 Assigning these to B Rydberg series yields 0.44
We study the infinite temperature dynamics of a prototypical one-dimensional system expected to exhibit many-body localization. Using numerically exact methods, we establish dynamical phase diagram this based on statistics its eigenvalues and behavior. show that nonergodic is reentrant as function interaction strength, illustrating localization can be reinforced by sufficiently strong interactions even at temperature. Surprisingly, within accessible time range, ergodic shows subdiffusive...
Molybdenum disulfide bilayers with well-defined interlayer twist angle were constructed by stacking single-crystal monolayers. Varying results in strong tuning of the indirect optical transition energy and second-harmonic generation weak direct energies Raman mode frequencies. Electronic structure calculations show separation changes due to repulsion between sulfur atoms, resulting shifts energies. These that alignment is a crucial variable tailoring properties two-dimensional heterostructures.
We report efficient nonradiative energy transfer (NRET) from core-shell, semiconducting quantum dots to adjacent two-dimensional sheets of graphene and MoS2 single- few-layer thickness. observe quenching the photoluminescence (PL) individual enhanced PL decay rates in time-resolved PL, corresponding 1-10 ns(-1). Our measurements reveal contrasting trends NRET rate dot van der Waals material as a function The increases significantly with increasing layer thickness graphene, but decreases...
Current nonequilibrium Monte Carlo methods suffer from a dynamical sign problem that makes simulating real-time dynamics for long times exponentially hard. We propose new `Inchworm Algorithm', based on iteratively reusing information obtained in previous steps to extend the propagation longer times. The algorithm largely overcomes problem, changing scaling exponential quadratic. use method solve Anderson impurity model Kondo and mixed valence regimes, obtaining results both quenches spin...
The idea to use quantum mechanical devices simulate other systems is commonly ascribed Feynman. Since the original suggestion, concrete proposals have appeared for simulating molecular and materials chemistry through computation, as a potential ``killer application''. Indications of exponential advantage in artificial tasks increased interest this application, thus, it critical understand basis chemistry. Here we gather evidence case most common task chemistry, namely, ground-state energy...
Abstract Lead-halide perovskites have emerged as promising materials for photovoltaic and optoelectronic applications. Their significantly anharmonic lattice motion, in contrast to conventional harmonic semiconductors, presents a conceptual challenge understanding the genesis of their exceptional properties. Here we report strongly temperature dependent luminescence Stokes shift electronic spectra both hybrid inorganic lead-bromide perovskite single crystals. This behavior stands stark that...
The development of halide perovskite semiconductors led to various technological breakthroughs in optoelectronics, particular the areas photovoltaics and light-emitting diodes. Additionally, study their fundamental properties has uncovered intriguing puzzles that demand explanation. Polaronic effects associated with coupling electrons holes polar lattice vibrations are often invoked as a microscopic mechanism explain unusual experimental observations. While some form polaronic behavior...
Recent experiments suggest that ground state chemical reactivity can be modified when placing molecular systems inside infrared cavities where vibrations are strongly coupled to electromagnetic radiation. This phenomenon lacks a firm theoretical explanation. Here, we employ an exact quantum dynamics approach investigate model of cavity-modified reactions in the condensed phase. The contains coupling reaction coordinate generic solvent, cavity either or non-reactive mode, and lossy modes....
Abstract Semiconductor excitations can hybridize with cavity photons to form exciton-polaritons (EPs) remarkable properties, including light-like energy flow combined matter-like interactions. To fully harness these EPs must retain ballistic, coherent transport despite matter-mediated interactions lattice phonons. Here we develop a nonlinear momentum-resolved optical approach that directly images in real space on femtosecond scales range of polaritonic architectures. We focus our analysis EP...