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HEISING-sIMONS POSTDOCTORAL fELLOWS

 

anthony poggioli

2020-2022 Heising-Simmons Postdoctoral Fellow

Faculty Advisor: Professor David Limmer

anthony.poggioli@ens.fr

Anthony's research focuses on the implementation of neural network techniques for approximating reactive force fields from ab initio molecular dynamics (AIMD) simulations. Such techniques combine the versatility of ab initio calculations with the reduced computational cost of classical MD simulations. In particular, Anthony is focused on applying these techniques in the investigation of hydroxylation dynamics at solid-liquid interfaces under strong (nanometric or angstrometric) confinement and in the presence of fluid shear. This will for the first time allow for the investigation of the self-consistency relations between surface charge and fluid flow, as fluid flow both influences and is driven by the effective surface charge density at the solid-liquid interface. This work represents a next step in the molecular theory of electrokinetic processes and is highly relevant to, e.g., topics in membrane science such as blue energy generation and desalination.
Before joining Kavli ENSI, Anthony received a PhD in physics from the Ecole Normale Superieure in Paris, and before that he studied environmental engineering and hydrodynamics. Previously, his research has focused on topics related to transport in buoyant environmental flows and to nonlinear ionic transport in nanometric and angstrometric channels.
 

Cong SUCong Su

2019-2021 Heising-Simons Postdoctoral Fellow

Faculty Advisor: Prof. Alex Zettl

csu@berkeley.edu

Cong Su's work focuses on modifying and controlling atomic-level structures in two-dimensional materials, including doping in the fabrication process, and modification using high energy electron beam after materials are made. Cong Su received his Ph.D. degree in Nuclear Science and Engineering from MIT in 2019, and a Bachelor's in physics from Yuanpei College, Peking University in 2013.

Peng Cheng ChenPengcheng Chen

2019-2021 Heising-Simons Postdoctoral Fellow

Faculty Advisor: Prof. Peidong Yang

pcchen@berkeley.edu

Pengcheng 's  research focuses on developing a hybrid nanocatalyst system that integrates semiconductor nanowires and multimetallic nanocrystals. The inherent properties of nanowire arrays, including large surface area and enhanced light scattering/absorption, make nanowire arrays attractive platforms to explore the synergy between multiple metals in a nanocrystal co-catalyst. Nanowires and nanocrystal co-catalysts will be combined to develop superior catalytic systems that increase the sustainability and efficiency of reactions such as water splitting, carbon dioxide reduction, and nitrogen reduction.

Before joining Kavli ENSI, Pengcheng received his Ph.D. in materials science and engineering from Northwestern University. His past research focuses on using scanning probe nanolithography to combinatorially synthesize polyelemental nanostructures and studying the phase-separation behavior of multiple metals at the nanoscale.

Shaowei LiShaowei Li

2018-2020 Heising-Simons Postdoctoral Fellow

Faculty Advisor: Prof. Michael Crommie

swli@berkeley.edu

Shaowei's research focuses on developing a novel imaging technique combing laser and a scanninbg tunneling microscope (STM) to shatter the diffraction limit and probe the inhomogeneous properties in low dimensional materials. The desire for observing finer details using optical microscopy particularly in bio-science and material-science is pushing technology developments beyond the diffraction limit. The coupling of photon excitation with electron tunneling at the junction of a scanning tunneling microscope combines the femtosecond sensitivity of a laser and the Angstrom resolution of tunneling electrons. The joint fs-A resolution will provide a new window for viewing the unique ultafast dynamics of individual nano-scale objects.

Shaowei received his Ph.D. in physics from UC Irvine in 2017. Prior to that, he received his bachelor degree in physics from Nankai University in 2010. He spent a year as a postdoctoral fellow at Northwestern University before joining ENSI. His past work involves probing the physcial and chemical properties of single molecules and low-dimensional materials with optical techniques and STM.

 

PHILOMATHIA GRADUATE STUDENT FELLOWS

 

jakob Dahl

2020-2021 Philomathia Graduate Student Fellow

Faculty Advisor: Paul Alivisatos 

jakobd@berkeley.edu

Jakob’s work focuses on understanding the physical chemistry of nanocrystal synthesis in lead halide and gold nanocrystals. While it is possible to make different sizes and shapes nanocrystals, scientists have only a rough, qualitative understanding of the chemical processes. Jakob uses in-situ observations in the Alivisatos lab and high-throughput experiments in the Chan lab to generate 1000s of datapoints on nanocrystal synthesis. Machine learning techniques help analyze this data. Currently, he is working with the Limmer and Persson groups to develop chemistry-based machine learning models that will quantify and clarify our understanding of the complex reaction networks involved in forming nanocrystals. The goal is to enable robust, chemical-model based predictions for nanocrystal yield, size, shape and composition for synthesis procedures that have not previously been attempted. Ideally, this will both speed up nanocrystal synthesis exploration and lead to enhanced understanding of the underlying chemical processes. 

Canxun zhang

2020-2021 Philomathia Graduate Student Fellow

Faculty Advisor: Michael Crommie

canxun_zhang@berkeley.edu

Canxun’s research focuses on investigating the electronic properties of graphene and/or transition metal dichalcogenide (TMD) based moiré systems using scanning tunneling microscopy and spectroscopy (STM/STS). Moiré superlattices are formed by stacking two layers of 2D materials with either a twist angle or a lattice mismatch. Driven by enhanced electron-electron interactions, novel quantum phases of matter such as Mott insulating states, superconductivity, nontrivial topology and orbital ferromagnetism can emerge in such systems. Canxun utilizes STM/STS to locally probe as well as manipulate the effects of correlation and topology in gate-tunable moiré systems. He will use the STM tip to actively control the electronic structure of the sample and to characterize the emerging correlation physics. He will also study naturally occurring topological domain boundaries or intentionally create such domain boundaries in order to detect topologically protected interface modes. 

Franklin liou

2020-2021 Philomathia Graduate Student Fellow

Faculty Advisor: Michael Crommie

fliou@berkeley.edu

Franklin‘s work focuses on studying the electronic properties of molecular nanostructures in a field-effect transistor configuration. As the size of electronic devices grow smaller, control over their precise structure becomes ever more important for obtaining consistent electronic behavior. Bottom-up synthesis from well-defined, rigid molecular building blocks offers a way to assemble atomically precise electronic materials. Franklin is using scanning tunneling microscopy and spectroscopy to study bottom-up synthesized molecular nanostructures such as covalent organic frameworks (COFs) and graphene nanoribbons grown within a graphene nanogap, with the goal of correlating the local electronic and atomic structure to global electronic transport properties of the material.

Nikita Hanikel

2020-2021 Philomathia Graduate Student Fellow 

Faculty Advisor: Professor Omar Yaghi

nikita.hanikel@berkeley.edu

Nikita’s work focuses on addressing the global water shortage crisis through development of next-generation sorbents, as well as their device-level implementation. His main research goal is the synthesis and study of new metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) that are suitable for atmospheric water harvesting in arid climates. In this context, he studies the water cluster formation within these crystalline frameworks by using a variety of crystallographic methods. This helps him to understand the water–framework interactions and consequently tune the material’s water sorption properties. In collaboration with Professor Ting Xu, Nikita intends to explore alternative approaches to freshwater generation and purification by employing MOF–polymer nanocomposites.

TREVOR ROBERTS

2019-2020 Philomathia Graduate Student Fellow

Faculty Advisor: Prof. Naomi Ginsberg

troberts@berkeley.edu

Trevor's work focuses on uncovering the mechanisms of energy transport in a range of light harvesting materials using ultrafast spectroscopy techniques. Correlating such materials’ morphology with their energetic landscape and transport functionality necessitates optical resolution on both spatial scales relevant to structural heterogeneities and temporal scales relevant to transport in the vicinity of such heterogeneities. By utilizing a time-resolved ultrafast super-resolution microscopy technique (time-resolved ultrafast STED, or TRUSTED), we have the capability to probe both the relevant time and length scales of excitation diffusion to characterize the extent structural anomalies like defects impede energy transport. In collaboration with the Alivisatos group, he will study semiconductor nanocrystal assemblies with varying degrees of predicted electronic coupling to elucidate the nature by which and the degree to which defects hamper energy transport in these distinct regimes.

JUSTIN ONDRY

2019-2020 Philomathia Graduate Student Fellow

Faculty Advisor: Prof. Paul Alivisatos

jondry@berkeley.edu

Justin’s work focuses on understanding imperfect oriented attachment of semiconductor nanocrystals using transmission electron microscopy (TEM).  Oriented attachment can be used to fuse individual nanocrystals into arrays of attached nanocrystals with long range crystallographic coherence. Unfortunately, improper attachment events can lead to dislocations and other structural defects which often have undesirable electronic properties.  Justin uses in-situ TEM to observe these defective interfaces while the defects are being annealed out of the material. The goal is to identify ideal attachment conditions to avoid defect formation, or if they are to form, have an easy way to be removed from the material. Once this is achieved, he intends to explore the potentially exotic electronic properties attached semiconductor nanocrystals are predicted to have. 

 

Former


HEISING-SIMONS POSTDOCTORAL FELLOWS

Luis Pazos

LUIS PAZOS-OUTON

2017-2019 Heising-Simons Postdoctoral Fellow 

Previous Faculty Advisor: Prof. Eli Yablonovitch

Current Position: Software Engineer at Google Brain

luispazos@google.com

Luis ' work focuses on the development of two different, yet strongly related, projects: A thermophotonic bottle for vaccine delivery and a thermophotovoltaic device. The former uses ultra efficient LEDs to cool the inner layer of a thermos bottle to keep its contents at stable temperatures for long periods, this can be critical for vaccine delivery in developing countries. The latter aims to transform heat into electricity, using light as the heat transfer medium. This could allow to create ultralight engines for spaceship applications.

 

Archana RajaArchana Raja

2017-2019 Heising-Simons Postdoctoral Fellow

Previous Faculty Advisor: Prof. Paul Alivisatos

Current Position: Project Scientist, LBNL

araja@lbl.gov 

  Archana worked on a number of projects involving optoelectronic processes of sub-nanometer thick two-dimensional (2D) materials, including uncovering a fundamentally new type of material disorder at the limit of atomically thin crystals, termed “dielectric disorder”.  This works was published at the journal Nature Nanotechnology.

 

Patrick GallagherPatrick Gallagher

2016-2018 Heising-Simons Postdoctoral Fellow

Previous Faculty Advisor: Prof. Feng Wang

Current Position: Scientist, Stealth-Mode

 Patrick is an experimental physicist. He studied two-dimensional (2D) systems of electrons, which can form on surfaces, at interfaces, or in atomically thin materials like graphene. Electrons confined to 2D exhibit phenomena not observed in 3D—and because a 2D system is entirely surface, with no interior, its electronic behavior can often be tuned by external perturbations such as electric fields. These properties make 2D systems attractive for fundamental studies and the development of new technologies.

 

PHILOMATHIA GRADUATE STUDENT FELLOWS 

MATTHEW GILBERT 

2018-2019 Philomathia Graduate Student Fellow

Previous Faculty Advisor: Prof. Alex Zettl 

Current Position: Postdoctoral Fellow, Sandia National Laboratory

m.gilbert@berkeley.edu 

Matthew's research focused on the chemical synthesis of and direct-write nanostructuring of the two-dimensional (2D) materials, graphene and hexagonal boron nitride (h-BN).   The goal of his work is to 1.) understand and control the properties of the large-scale chemical synthesis of high-quality 2D materials, 2.) to develop new methods for the fabrication of nanostructures (e.g. nanoribbons, nanopores, nanopatterned heterostructures, etc.) in these 2D sheets, and 3.) to explore the applications of these materials for nanoscale sensing.

 

CHRISTIAN DIERKS

2017-2018 Philomathia Graduate Student Fellow                                                                                                                             

Previous Faculty Advisor: Prof. Omar Yaghi

Current Position: Postdoctoral Fellow, The Scripps Research Institute

c.diercks@berkeley.edu

Christian's research focused on covalent organic frameworks (COFs) for the electrocatalytic reduction of carbon dioxide to carbon monoxide. The grand challenge in photo- and electrocatalytic carbon dioxide reduction to value-added carbon products lies in the fact that a singular catalytic system must control the interplay between efficiency, activity, and selectivity and we believe that the reticular chemistry of COFs can address it.

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