A5051301656- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Photocathodes and Microchannel Plates
- Integrated Water Resources Management
- Quantum Dots Synthesis And Properties
- Chalcogenide Semiconductor Thin Films
- Electron and X-Ray Spectroscopy Techniques
- Gyrotron and Vacuum Electronics Research
- Advanced Electron Microscopy Techniques and Applications
- Superconducting Materials and Applications
- Particle Detector Development and Performance
- Geology and Environmental Impact Studies
- Plasma Diagnostics and Applications
- Radiation Therapy and Dosimetry
- Botany and Plant Ecology Studies
- Advanced X-ray Imaging Techniques
- Copper-based nanomaterials and applications
- Radiation Detection and Scintillator Technologies
- Urban Development and Cultural Heritage
- Flood Risk Assessment and Management
- Nanocluster Synthesis and Applications
- Urban Stormwater Management Solutions
- Gold and Silver Nanoparticles Synthesis and Applications
- Infrastructure Resilience and Vulnerability Analysis
- Perovskite Materials and Applications
University of Łódź
2013-2025
Cornell University
2015-2024
Brookhaven National Laboratory
2017-2022
University of Chicago
2022
University of Salerno
2022
Instytut Nauk Geologicznych
2015
Instituto de Geociencias
2015
University of Pennsylvania
2010-2011
Wuhan University
2008
Injection of photoexcited electrons from colloidal PbS quantum dots into TiO2 nanoparticles is investigated. The electron affinity and ionization potential dots, inferred cyclic voltammetry measurements, show strong size dependence due to confinement. On the basis measured energy levels, should transfer efficiently only for quantum-dot diameter below ∼4.3 nm. Continuous-wave fluorescence spectra transients coupled titanium dioxide are consistent with small dots. time surprisingly slow (∼100...
We report the design, fabrication, and characterization of colloidal PbSe nanocrystal (NC)-based photovoltaic test structures that exhibit an excitonic solar cell mechanism. Charge extraction from NC active layer is driven by a photoinduced chemical potential energy gradient at nanostructured heterojunction. By minimizing perturbation to levels thereby gaining insight into "intrinsic" properties charge transfer mechanism NC, we show direct correlation between interfacial level offsets device...
Internanocrystal coupling induced excitons dissociation in lead salt nanocrystal assemblies is investigated. By combining transient photoluminescence spectroscopy, grazing incidence small-angle X-ray scattering, and time-resolved electric force microscopy, we show that can dissociate, without the aid of an external bias or chemical potential gradient, via tunneling through a barrier when energy comparable to exciton binding energy. Our results have important implications for design...
Monodisperse, high-quality, single-crystal PbSe nanorods were synthesized in a catalyst-free, one-pot reaction using new phosphine selenide precursor. assembled to provide liquid-crystalline alignment or vertical under controlled evaporation conditions. The growth of was monitored by TEM and absorption spectroscopy, indicating that oriented attachment could be involved anisotropic nanostructures. In-plane XRD showed an enhanced (200) peak for nanorods, the preferred on substrates their along...
High-power, high-brightness electron beams are of interest for many applications, especially as drivers free lasers and energy recovery linac light sources. For these particular photoemission injectors used in most cases, the initial beam brightness from injector sets a limit on quality generated at end accelerator. At Cornell University, we have built such high-power using DC gun followed by superconducting accelerating module. Recent results will be presented demonstrating record setting...
A theory of the electronic-structure and excitonic absorption spectra PbS PbSe nanowires nanorods in framework a four-band effective-mass model is presented. Calculations conducted for show that dielectric contrast dramatically strengthens exciton binding narrow nanorods. However, self-interaction energies electron hole nearly cancel Coulomb binding, as result optical are practically unaffected by strong between surrounding medium. Measurements size-dependent colloidal also Using...
We report the first observation of electrogenerated chemiluminescence (ECL) from PbS quantum dots (QDs). Different ECL intensities are observed for different ligands used to passivate QDs, which indicates that is sensitive surface chemistry, with potential serve as a powerful probe states and charge transfer dynamics in QDs. In particular, passivation QD surfaces trioctylphosphine (TOP) increases intensity by 3 orders magnitude when compared oleic acid alone. The overlap photoluminescence...
We present a detailed study of the six-dimensional phase space electron beam produced by Cornell Energy Recovery Linac Photoinjector, high-brightness, high repetition rate (1.3 GHz) DC photoemission source designed to drive hard x-ray energy recovery linac (ERL). A complete simulation model injector has been constructed, verified measurement, and optimized. Both horizontal vertical 2D transverse spaces, as well time-resolved (sliced) space, were simulated directly measured at end for 19 77...
Theoretical and experimental investigations of the behavior normal-dispersion fiber lasers with nonlinear optical loop mirrors are presented. The use a mirror causes laser to generate relatively long, flat-topped pulses. pulse energy can be high, but duration is limited greater than 300 fs. Experimentally, 8 nJ pulses that dechirped 340 fs obtained. step toward an all-fiber, environmentally stable design.
High quantum yield, low transverse energy spread, and prompt response time make GaAs activated to negative electron affinity an ideal candidate for a photocathode in high brightness photoinjectors. Even after decades of investigation, the exact mechanism emission from is not well understood. Here, photoemission such photocathodes modeled using detailed Monte Carlo transport simulations. Simulations show quantitative agreement with experimental results efficiency, distributions emitted...
The roles of solvent reorganization energy and electronic coupling strength on the transfer photoexcited electrons from PbS nanocrystals to TiO2 nanoparticles are investigated. We find that electron depends only weakly solvent, in contrast strong dependence nanocrystal–molecule system. This is ascribed larger size acceptor this system, accounted for by Marcus theory. varied changing length, aliphatic aromatic structure, anchor groups linker molecules. Shorter molecules consistently lead...
Transfer of photoexcited charge from PbS nanocrystals to ligand molecules is investigated in different solvents. We find that the transfer rate increases dramatically with solvent dielectric constant. This trend accounted for by a modified Marcus theory incorporates only static effects. The choice allows significant control process. As an important example, we dispersed water exhibit rates 1000 times higher than same organic solvent. Rapid extraction will be efficient nanocrystal-based...
We present the results of transverse emittance and longitudinal current profile measurements high bunch charge (≥100 pC) beams produced in DC gun-based Cornell energy recovery linac photoinjector. In particular, we show that cathode thermal core beam emittances dominate final 95% measured at 9–9.5 MeV. Additionally, demonstrate excellent agreement between optimized 3D space simulations measurement, quality laser distribution limits optimal simulated emittances. These results, previously...
Energy recovery has been achieved in a multipass linear accelerator, demonstrating technology for more compact particle accelerators operating at higher currents and reduced energy consumption. delivered to the beam during first four passes through accelerating structure was recovered subsequent decelerating passes. High-energy efficiency by use of superconducting cavities permanent magnets. The fixed-field alternating-gradient optical system used return loop successfully transported...
Driven by life-science applications, a mega-electron-volt Scanning Transmission Electron Microscope (MeV-STEM) has been proposed here to image thick frozen biological samples as conventional (TEM) may not be suitable thicker than 300–500 nm and various volume electron microscopy (EM) techniques either suffering from low resolution, or speed. The high penetration of inelastic scattering signals MeV electrons could make the MeV-STEM an appropriate microscope for 10 μm more with nanoscale...
The electronic structure of $\mathrm{Pb}\mathrm{Se}∕\mathrm{Pb}\mathrm{S}$ core-shell quantum dots (QDs) is calculated within a four-band envelope function formalism. effective mass approximation used successfully to model PbS and PbSe core QDs extended include discontinuities in material parameters. shows that even though type-II heterostructure, for typical dot sizes properties will not be observed. Instead, the wave functions are predicted extend throughout both materials. Experimental...
Characterization of 9--9.5 MeV electron beams produced in the dc-gun based Cornell photoinjector is given for bunch charges ranging from 20 pC to 2 nC. Comparison measured emittances and longitudinal current profiles optimized 3D space charge simulations yields excellent agreement up 1 nC when laser distribution used generate initial particle distributions simulation. Analysis scaling emittance with shows that scales roughly as square root 300 pC, above which trend becomes linear. These...
Measurements of the intrinsic emittance and response time a Cs3Sb photocathode are presented. The is obtained with solenoid scan technique using high voltage dc photoemission gun. Photoemission evaluated RF deflecting cavity synchronized to picosecond laser pulse train. We find that has both small mean transverse energy, 160 ± 10 meV at 532 nm wavelength, prompt (below resolution our measurement) making it suitable material for brightness electron photoinjectors.
PbS quantum dots (QDs) are functionalized using ionic liquids with thiol moieties as capping ligands. The resulting amphiphilic QD exhibit fluidlike behavior at room temperature, even in the absence of solvents. photostability QDs is dramatically improved compared to as-synthesized oleic acid-capped dispersed toluene. Detailed facts importance specialist readers published "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset. They made available submitted by...
Thermal emittance measurements of a CsK2Sb photocathode at several laser wavelengths are presented. The is obtained with solenoid scan technique using high voltage dc photoemission gun. thermal 0.56+/-0.03 mm-mrad/mm(rms) 532 nm wavelength. results compared simple model and found to be in good agreement.
We report the design and performance of a time-resolved electron diffraction apparatus capable producing intense bunches with simultaneously single digit micrometer probe size, long coherence length, 200 fs rms time resolution. measure 5d (peak) beam brightness at sample location in micro-diffraction mode to be 7×1013 A/m2 rad2 . To generate high bunches, system employs efficiency, low emittance semiconductor photocathodes driven wavelength near photoemission threshold repetition rate up 250...
Sodium potassium antimonide photocathodes with Quantum Efficiency (QE) in the range of few percent have been grown, and their photoemission properties are measured. We report intrinsic emittance response time electron bunches extracted from this material. It is possible to recover QE an overheated cathode by simple addition, rugged enough deliver tens mA average current no or minimal degradation.