A5065693701- Molecular Junctions and Nanostructures
- Diamond and Carbon-based Materials Research
- Advanced biosensing and bioanalysis techniques
- Analytical Chemistry and Sensors
- Force Microscopy Techniques and Applications
- Quantum and electron transport phenomena
- Plasmonic and Surface Plasmon Research
- High-pressure geophysics and materials
- Metamaterials and Metasurfaces Applications
- Atomic and Subatomic Physics Research
- Surface Chemistry and Catalysis
- DNA and Nucleic Acid Chemistry
- Mechanical and Optical Resonators
- Ion-surface interactions and analysis
- Quantum-Dot Cellular Automata
- Computational Physics and Python Applications
- Carbon Nanotubes in Composites
- Nanofabrication and Lithography Techniques
- Electronic and Structural Properties of Oxides
- Microwave Engineering and Waveguides
- ZnO doping and properties
- Nanowire Synthesis and Applications
- GaN-based semiconductor devices and materials
- Advanced X-ray Imaging Techniques
- Quantum optics and atomic interactions
ETH Zurich
2021-2025
University of California, Los Angeles
2015-2021
California NanoSystems Institute
2015-2021
Stanford University
2020-2021
Northwestern University
2017
International Institute for Nanotechnology
2017
University of Florida
2012
Transistor sensing in salt solutions Molecular binding to receptors on the surface of field-effect transistors (FETs) can be sensed through changes transconductance. However, saline typically used with biomolecules create an electrical double layer that masks any events occur within about 1 nanometer from surface. Nakatsuka et al. overcame this limitation by using large, negatively charged DNA stem loop structures that, upon ligand binding, cause conformational FET, even high ionic strength....
The fundamental role of halide anions in the seed-mediated synthesis anisotropic noble metal nanostructures has been a subject debate within nanomaterials community. Herein, we systematically investigate roles chloride, bromide and iodide mediating growth Au nanostructures. A high-purity surfactant solution hexadecyltrimethylammonium (CTABr) is used to reliably probe each anion without interference from impurities. Our investigation reveals that are required for formation nanorods, while...
Optical control and readout of electron spin currents in thin films nanostructures have remained attractive yet challenging goals for emerging technologies designed applications information processing storage. Recent advances room-temperature polarization using nanometric chiral molecular assemblies suggest that chemically modified surfaces or interfaces can be used optical conversion by exploiting photoinduced charge separation injection from well-coupled organic chromophores quantum dots....
Understanding spin-selective interactions between electrons and chiral molecules is critical to elucidating the significance of electron spin in biological processes assessing potential assemblies for organic spintronics applications. Here, we use fluorescence microscopy visualize effects spin-dependent charge transport self-assembled monolayers double-stranded DNA on ferromagnetic substrates. Patterned arrays provide background regions every measurement enable quantification substrate...
X-ray-based analytics are routinely applied in many fields, including physics, chemistry, materials science, and engineering. The full potential of such techniques the life sciences medicine, however, has not yet been fully exploited. We highlight current upcoming advances this direction. describe different methodologies (including those performed at synchrotron light sources X-ray free-electron lasers) their potentials for application to investigate nano–bio interface. discussion is...
Oligonucleotide receptors (aptamers), which change conformation upon target recognition, enable electronic biosensing under high ionic-strength conditions when coupled to field-effect transistors (FETs). Because highly negatively charged aptamer backbones are influenced by ion content and concentration, biosensor performance sensitivities were evaluated application conditions. For a recently identified dopamine aptamer, physiological concentrations of Mg2+ Ca2+ in artificial cerebrospinal...
Genetic analysis methods are foundational to advancing personalized and preventative medicine, accelerating disease diagnostics, monitoring the health of organisms ecosystems. Current nucleic acid technologies such as polymerase chain reaction (PCR), next-generation sequencing (NGS), DNA microarrays rely on fluorescence absorbance, necessitating sample amplification or replication leading increased processing time cost. Here, we introduce a label-free genetic screening platform based high...
Spin selectivity in photo-emission from ferromagnetic substrates functionalized with chiral organic films was analyzed by ultraviolet photoelectron spectroscopy at room temperature. Using radiation photon energy greater than the ionization potential of adsorbed molecules, photoelectrons were collected that originated both underlying and films, kinetic energies range ca. 0–18 eV. We investigated composed self-assembled monolayers α-helical peptides electrostatically protein, bovine serum...
We detect short oligonucleotides and distinguish between sequences that differ by a single base, using label-free, electronic field-effect transistors (FETs). Our sensing platform utilizes ultrathin-film indium oxide FETs chemically functionalized with single-stranded DNA (ssDNA). The ssDNA-functionalized semiconducting channels in fully complementary differentiate these from those having different types locations of base-pair mismatches. Changes charge associated surface-bound ssDNA vs...
Strong enhancement of molecular circular dichroism has the potential to enable efficient asymmetric photolysis, a method chiral separation that conventionally been impeded by insufficient yield and low enantiomeric excess. Here, we study experimentally how predicted enhancements in optical chirality density near resonant silicon nanodisks boost dichroism. We use fluorescence-detected spectroscopy measure indirectly differential absorption circularly polarized light monolayer optically active...
We designed and fabricated large arrays of polymer pens having sub-20 nm tips to perform chemical lift-off lithography (CLL). As such, we developed a hybrid patterning strategy called polymer-pen (PPCLL). demonstrated PPCLL using pyramidal v-shaped arrays. Associated simulations revealed nanometer-scale quadratic relationship between contact line widths the two other variables: base vertical compression distances. devised stamp support system consisting interspersed flat-tipped that are...
Abstract Nuclear magnetic resonance imaging (MRI) at the atomic scale offers exciting prospects for determining structure and function of individual molecules proteins. Quantum defects in diamond have recently emerged as a promising platform towards reaching this goal, allowed detection localization single nuclear spins under ambient conditions. Here, we present an efficient strategy extending to large spin clusters, fulfilling important requirement single-molecule MRI technique. Our method...
Nuclear magnetic resonance (NMR) imaging with shallow nitrogen–vacancy (NV) centers in diamond offers an exciting route toward sensitive and localized chemical characterization at the nanoscale. Remarkable progress has been made to combat degradation coherence time stability suffered by near-surface NV using suitable surface termination. However, approaches that also enable robust control over adsorbed molecule density, orientation, binding configuration are needed. We demonstrate a...
We present an open-source simulation framework for optically detected magnetic resonance, developed in Python. The allows users to construct, manipulate, and evolve multipartite quantum systems that consist of spins electronic levels. provide interface efficient time-evolution Lindblad form as well a facilitating spatial generalized stochastic dynamics. Further, symbolic operator construction propagation is supported simple model making the also ideal use classroom instruction resonance....
Scanning magnetometry with nitrogen-vacancy (NV) centers in diamond has led to significant advances the sensitive imaging of magnetic systems. The spatial resolution technique, however, remains limited tens hundreds nanometers, even for probes where NV are engineered within 10 nm from tip apex. Here, we present a correlated investigation crucial parameters that determine resolution: mechanical and stand-off distances, as well subsurface center depth diamond. We study their contributions...
Abstract All‐optical control and detection of magnetic states for high‐density recording necessitate nanophotonic approaches to amplify local light intensity below the diffraction limit. Sculpting near‐field phase polarization can additionally strengthen magneto‐optical effects that rely on circularly polarized pulses, such as all‐optical helicity‐dependent switching, imaging, spin‐wave excitation. Here, high‐refractive‐index dielectric nanoantennas illuminated with resonantly enhance...
We report spatially resolved measurements of static and fluctuating electric fields over conductive (Au) nonconductive (SiO_{2}) surfaces. Using an ultrasensitive "nanoladder" cantilever probe to scan these surfaces at distances a few tens nanometers, we record changes in the resonance frequency damping that associate with fields, respectively. find be correlated. Furthermore, are similar magnitude for two materials. quantitatively describe observed effects on basis trapped surface charges...
A vibronic resonance between Au{111} surface states and adsorbed CN vibrations has been predicted, which we target for study. We have formed stable monolayers of cyanide on observe a hexagonal close-packed lattice with nearest neighbor distance 3.8 ± 0.5 Å. Cyanide orients normal to the attached via Au–C bond. show that substrate–molecule coupling is particularly strong, leading ultrafast electron transfer from molecules substrate as measured by resonant Auger spectroscopy using core–hole...
Spin-dependent and enantioselective electron–molecule scattering occurs in photoelectron transmission through chiral molecular films. This spin selectivity leads to electron filtering by helices, with increasing magnitude concomitant numbers of helical turns. Using ultraviolet spectroscopy, we measured spin-selective surface charging accompanying photoemission from ferromagnetic substrates functionalized monolayers mercurated DNA hairpins that constitute only one turn. Mercury ions bind...
Photoexcitable donor-bridge-acceptor (D-B-A) molecules that support intramolecular charge transfer are ideal platforms to probe the influence of chiral induced spin selectivity (CISS) in electron and resulting radical pairs. In particular, extent which CISS influences polarization or coherence initial state spin-correlated pairs following through a bridge remains an open question. Here, we introduce quantum sensing scheme measure directly hypothesized using shallow nitrogen-vacancy (NV)...