Shira Yochelis - Academia.edu (original) (raw)

Papers by Shira Yochelis

Research paper thumbnail of Dynamic Spin-Controlled Enantioselective Catalytic Chiral Reactions

The Journal of Physical Chemistry Letters

Research paper thumbnail of Universal proximity effects in hybrid superconductor–linker molecule–nanoparticle systems: The effect of molecular chirality

Research paper thumbnail of Molecular Fingerprint Detection: Molecular Fingerprint Detection Using Portable Water‐Compatible Electronic Tunneling Spectroscopy Device (Adv. Mater. Interfaces 19/2020)

Advanced Materials Interfaces

Research paper thumbnail of Tuning Quantum Dots Coupling Using Organic Linkers with Different Vibrational Modes

Research paper thumbnail of Room-Temperature Inter-Dot Coherent Dynamics in Multilayer Quantum Dot Materials

The full blossoming of quantum technologies requires the availability of easy-to-prepare material... more The full blossoming of quantum technologies requires the availability of easy-to-prepare materials where quantum coherences can be effectively initiated, controlled, and exploited, preferably at ambient conditions. Solid-state multilayers of colloidally grown quantum dots (QDs) are highly promising for this task because of the possibility of assembling networks of electronically coupled QDs through the modulation of sizes, inter-dot linkers, and distances. To usefully probe coherence in these materials, the dynamical characterization of their collective quantum mechanically coupled states is needed. Here, we explore by two-dimensional electronic spectroscopy the coherent dynamics of solid-state multilayers of electronically coupled colloidally grown CdSe QDs and complement it by detailed computations. The time evolution of a coherent superposition of states delocalized over more than one QD was captured at ambient conditions. We thus provide important evidence for inter-dot coherences in such solid-state materials, opening up new avenues for the effective application of these materials in quantum technologies.

Research paper thumbnail of Molecular Fingerprint Detection Using Portable Water‐Compatible Electronic Tunneling Spectroscopy Device

Advanced Materials Interfaces

Research paper thumbnail of Marine cyanobacteria tune energy transfer efficiency in their light‐harvesting antennae by modifying pigment coupling

Research paper thumbnail of Room Temperature Inter-Dot Coherent Dynamics in Multilayers Quantum Dot Materials

The full blossoming of quantum technologies requires the availability of easy-to-prepare material... more The full blossoming of quantum technologies requires the availability of easy-to-prepare materials where quantum coherences can be effectively initiated, controlled and exploited, preferably at ambient conditions. Solid-state multilayers of colloidally grown quantum dots (QDs) are highly promising for this task because of the possibility of assembling networks of electronically coupled QDs through the modulation of sizes, inter-dot linkers and distances. To usefully probe coherence in these materials, the dynamical characterization of their collective quantum mechanically coupled states is needed. Here we explore by 2D electronic spectroscopy the coherent dynamics of solid-state multilayers of electronically coupled colloidally grown CdSe QDs and complement it by detailed computations. The time evolution of a coherent superposition of states delocalized over more than one QD was captured at ambient conditions. We thus provide important evidence for inter-dot coherences in such solid...

Research paper thumbnail of Coupling effects in QD dimers at sub-nanometer interparticle distance

Nano Research

Currently, intensive research efforts focus on the fabrication of meso-structures of assembled co... more Currently, intensive research efforts focus on the fabrication of meso-structures of assembled colloidal quantum dots (QDs) with original optical and electronic properties. Such collective features originate from the QDs coupling, depending on the number of connected units and their distance. However, the development of general methodologies to assemble colloidal QD with precise stoichiometry and particle-particle spacing remains a key challenge. Here, we demonstrate that dimers of CdSe QDs, stable in solution, can be obtained by engineering QD surface chemistry, reducing the surface steric hindrance and favoring the link between two QDs. The connection is made by using alkyl dithiols as bifunctional linkers and different chain lengths are used to tune the interparticle distance from few nm down to 0.5 nm. The spectroscopic investigation highlights that coupling phenomena between the QDs in dimers are strongly dependent on the interparticle distance and QD size, ultimately affecting...

Research paper thumbnail of Selective enantiomer purification using magnetic oriented interacting microparticles

Separation and Purification Technology

Research paper thumbnail of The electron spin as a chiral reagent

Research paper thumbnail of Quantum Dot Coupling in a Vertical Transport Device under Ambient Conditions

ACS Omega

The semiconductor device industry is constantly challenged by the demands of miniaturization. The... more The semiconductor device industry is constantly challenged by the demands of miniaturization. Therefore, the use of nanomaterials, such as quantum dots (QDs), is expected. At these scales, quantum effects are anticipated under industrial working conditions. Here, we present a simple fabrication method for integrating colloidal coupled QDs as components in a vertical device. Characterization of the fundamental properties of QDs as an ensemble of isolated particles and as layered QD hybrid structures is demonstrated. For the case of layered QD hybrid structures, coupling between dots is on average stronger with typical energy band gaps reduced by more than 200 meV. The shown device offers a straightforward method to measure and establish a strong coupling transport system under ambient conditions.

Research paper thumbnail of AFM‐Based Spin‐Exchange Microscopy Using Chiral Molecules

Research paper thumbnail of Magnetic-related states and order parameter induced in a conventional superconductor by nonmagnetic chiral molecules

Nano Letters

Hybrid ferromagnetic/superconducting systems are well known for hosting intriguing phenomena such... more Hybrid ferromagnetic/superconducting systems are well known for hosting intriguing phenomena such as emergent triplet superconductivity at their interfaces and the appearance of in-gap, spin polarized Yu-Shiba-Rusinov (YSR) states bound to magnetic impurities on a superconducting surface. In this work we demonstrate that similar phenomena can be induced on a surface of a conventional superconductor by chemisorbing non-magnetic chiral molecules. Conductance spectra measured on NbSe2 flakes over which chiral alpha helix polyalanine molecules were adsorbed, exhibit, in some cases, in-gap states nearly symmetrically positioned around zero bias that shift with magnetic field, akin to YSR states, as corroborated by theoretical simulations. Other samples show evidence for a collective phenomenon of hybridized YSR-like states giving rise to unconventional, possibly triplet superconductivity, manifested in the conductance spectra by the appearance of a zero bias conductance that diminishes, but does not split, with magnetic field. The transition between these two scenarios appears to be governed by the density of adsorbed molecules.

Research paper thumbnail of Spin-Exciton Delocalization Enhancement in Multilayer Chiral Linker/Quantum Dot Structures

The Journal of Physical Chemistry Letters

Research paper thumbnail of Fast Energy Transfer in CdSe Quantum Dot Layered Structures: Controlling Coupling with Covalent-Bond Organic Linkers

The Journal of Physical Chemistry C

A home-built ultrafast transient absorption setup was used in measurements, as detailed here: an ... more A home-built ultrafast transient absorption setup was used in measurements, as detailed here: an amplified, Fourier limited compressed pulses were used to feed the setup (4mJ, 35fs pulses, around central wavelength of 800nm, at a repetition rate of 1kHz). The beam was split in two to generate a 400nm pump using a frequency-doubling crystal (BBO), and a white-light supercontinuum probe, by focusing it onto a 3mm thick sapphire plate. Pump pulses were attenuated to intensities of few µJ/cm 2 at the sample plane, to achieve an average excitation per QD of ~0.02 1 ex N <<. Pump beam was chopped at half of the working frequency (i.e., 500Hz) to create pumpprobe-probe sequences, with temporal separation between pump and probe pulses controlled by a motorized delay line. Absorption difference between pumped and unpumped state of the sample were measured at a selected probe wavelength. Time resolution of the experiment, as determined from pump-probe intensity correlation is around 150fs.

Research paper thumbnail of Simple fabrication of SWIR detectors based on wet deposition of carbon nanotubes and quantum dots

Sensors and Actuators A: Physical

Research paper thumbnail of Optical Chiral Induced Spin Selectivity XMCD Study

CHIMIA International Journal for Chemistry

Research paper thumbnail of Marine Cyanobacteria Tune Energy Transfer Efficiency in their Light-harvesting Antennae by Modifying Pigment Coupling

Photosynthetic organisms regulate energy transfer to fit to changes in environmental conditions. ... more Photosynthetic organisms regulate energy transfer to fit to changes in environmental conditions. The biophysical principles underlying the flexibility and efficiency of energy transfer in the light-harvesting process are still not fully understood. Here we examine how energy transfer is regulated in-vivo. We compare different acclimation states of the photosynthetic apparatus in a marine cyanobacterial species that is well adapted to vertical mixing of the ocean water column and identify a novel acclimation strategy for photosynthetic life under low light intensities. Antennae rods extend, as expected, increasing light absorption. Surprisingly, in contrast to what was known for plants and predicted by classic calculations, these longer rods transfer energy faster i.e. more efficiently. The fluorescence lifetime and emission spectra dependence on temperature, at the range of 4-300K, suggests that energy transfer efficiency is tuned by modifying the energetic coupling strength between...

Research paper thumbnail of Unconventional order parameter induced by helical chiral molecules adsorbed on a metal proximity coupled to a superconductor

Physical Review B

Following our previous results, which provide evidence for the emergence of a chiral p-wave tripl... more Following our previous results, which provide evidence for the emergence of a chiral p-wave triplet-pairing component in superconducting Nb upon the adsorption of chiral molecules, we turned to investigate whether such an effect can take place in a proximal superconductor consisting of metal on superconductor bilayer. Note that in such proximity systems, correlated electron-hole (Andreev) pairs exist in the normal metal rather than genuine Cooper pairs. To that end, we used scanning tunneling spectroscopy (STS) on thin Au films grown in-situ on NbN (a conventional s-wave superconductor) before and after adsorbing helical chiral, alpha-helix polyalanine molecules. The tunneling spectra measured on the pristine Au surface showed conventional (swave like) proximity gaps. However, upon molecules adsorption the spectra significantly changed, all exhibiting a zero-bias conductance peak embedded inside a gap, indicating unconventional superconductivity. The peak reduced with magnetic field but did not split, consistent with equal-spin triplet-pairing p-wave symmetry. In contrast, adsorption of nonhelical chiral cysteine molecules did not yield any apparent change in the order parameter, and the tunneling spectra exhibited only gaps free of in-gap structure.

Research paper thumbnail of Dynamic Spin-Controlled Enantioselective Catalytic Chiral Reactions

The Journal of Physical Chemistry Letters

Research paper thumbnail of Universal proximity effects in hybrid superconductor–linker molecule–nanoparticle systems: The effect of molecular chirality

Research paper thumbnail of Molecular Fingerprint Detection: Molecular Fingerprint Detection Using Portable Water‐Compatible Electronic Tunneling Spectroscopy Device (Adv. Mater. Interfaces 19/2020)

Advanced Materials Interfaces

Research paper thumbnail of Tuning Quantum Dots Coupling Using Organic Linkers with Different Vibrational Modes

Research paper thumbnail of Room-Temperature Inter-Dot Coherent Dynamics in Multilayer Quantum Dot Materials

The full blossoming of quantum technologies requires the availability of easy-to-prepare material... more The full blossoming of quantum technologies requires the availability of easy-to-prepare materials where quantum coherences can be effectively initiated, controlled, and exploited, preferably at ambient conditions. Solid-state multilayers of colloidally grown quantum dots (QDs) are highly promising for this task because of the possibility of assembling networks of electronically coupled QDs through the modulation of sizes, inter-dot linkers, and distances. To usefully probe coherence in these materials, the dynamical characterization of their collective quantum mechanically coupled states is needed. Here, we explore by two-dimensional electronic spectroscopy the coherent dynamics of solid-state multilayers of electronically coupled colloidally grown CdSe QDs and complement it by detailed computations. The time evolution of a coherent superposition of states delocalized over more than one QD was captured at ambient conditions. We thus provide important evidence for inter-dot coherences in such solid-state materials, opening up new avenues for the effective application of these materials in quantum technologies.

Research paper thumbnail of Molecular Fingerprint Detection Using Portable Water‐Compatible Electronic Tunneling Spectroscopy Device

Advanced Materials Interfaces

Research paper thumbnail of Marine cyanobacteria tune energy transfer efficiency in their light‐harvesting antennae by modifying pigment coupling

Research paper thumbnail of Room Temperature Inter-Dot Coherent Dynamics in Multilayers Quantum Dot Materials

The full blossoming of quantum technologies requires the availability of easy-to-prepare material... more The full blossoming of quantum technologies requires the availability of easy-to-prepare materials where quantum coherences can be effectively initiated, controlled and exploited, preferably at ambient conditions. Solid-state multilayers of colloidally grown quantum dots (QDs) are highly promising for this task because of the possibility of assembling networks of electronically coupled QDs through the modulation of sizes, inter-dot linkers and distances. To usefully probe coherence in these materials, the dynamical characterization of their collective quantum mechanically coupled states is needed. Here we explore by 2D electronic spectroscopy the coherent dynamics of solid-state multilayers of electronically coupled colloidally grown CdSe QDs and complement it by detailed computations. The time evolution of a coherent superposition of states delocalized over more than one QD was captured at ambient conditions. We thus provide important evidence for inter-dot coherences in such solid...

Research paper thumbnail of Coupling effects in QD dimers at sub-nanometer interparticle distance

Nano Research

Currently, intensive research efforts focus on the fabrication of meso-structures of assembled co... more Currently, intensive research efforts focus on the fabrication of meso-structures of assembled colloidal quantum dots (QDs) with original optical and electronic properties. Such collective features originate from the QDs coupling, depending on the number of connected units and their distance. However, the development of general methodologies to assemble colloidal QD with precise stoichiometry and particle-particle spacing remains a key challenge. Here, we demonstrate that dimers of CdSe QDs, stable in solution, can be obtained by engineering QD surface chemistry, reducing the surface steric hindrance and favoring the link between two QDs. The connection is made by using alkyl dithiols as bifunctional linkers and different chain lengths are used to tune the interparticle distance from few nm down to 0.5 nm. The spectroscopic investigation highlights that coupling phenomena between the QDs in dimers are strongly dependent on the interparticle distance and QD size, ultimately affecting...

Research paper thumbnail of Selective enantiomer purification using magnetic oriented interacting microparticles

Separation and Purification Technology

Research paper thumbnail of The electron spin as a chiral reagent

Research paper thumbnail of Quantum Dot Coupling in a Vertical Transport Device under Ambient Conditions

ACS Omega

The semiconductor device industry is constantly challenged by the demands of miniaturization. The... more The semiconductor device industry is constantly challenged by the demands of miniaturization. Therefore, the use of nanomaterials, such as quantum dots (QDs), is expected. At these scales, quantum effects are anticipated under industrial working conditions. Here, we present a simple fabrication method for integrating colloidal coupled QDs as components in a vertical device. Characterization of the fundamental properties of QDs as an ensemble of isolated particles and as layered QD hybrid structures is demonstrated. For the case of layered QD hybrid structures, coupling between dots is on average stronger with typical energy band gaps reduced by more than 200 meV. The shown device offers a straightforward method to measure and establish a strong coupling transport system under ambient conditions.

Research paper thumbnail of AFM‐Based Spin‐Exchange Microscopy Using Chiral Molecules

Research paper thumbnail of Magnetic-related states and order parameter induced in a conventional superconductor by nonmagnetic chiral molecules

Nano Letters

Hybrid ferromagnetic/superconducting systems are well known for hosting intriguing phenomena such... more Hybrid ferromagnetic/superconducting systems are well known for hosting intriguing phenomena such as emergent triplet superconductivity at their interfaces and the appearance of in-gap, spin polarized Yu-Shiba-Rusinov (YSR) states bound to magnetic impurities on a superconducting surface. In this work we demonstrate that similar phenomena can be induced on a surface of a conventional superconductor by chemisorbing non-magnetic chiral molecules. Conductance spectra measured on NbSe2 flakes over which chiral alpha helix polyalanine molecules were adsorbed, exhibit, in some cases, in-gap states nearly symmetrically positioned around zero bias that shift with magnetic field, akin to YSR states, as corroborated by theoretical simulations. Other samples show evidence for a collective phenomenon of hybridized YSR-like states giving rise to unconventional, possibly triplet superconductivity, manifested in the conductance spectra by the appearance of a zero bias conductance that diminishes, but does not split, with magnetic field. The transition between these two scenarios appears to be governed by the density of adsorbed molecules.

Research paper thumbnail of Spin-Exciton Delocalization Enhancement in Multilayer Chiral Linker/Quantum Dot Structures

The Journal of Physical Chemistry Letters

Research paper thumbnail of Fast Energy Transfer in CdSe Quantum Dot Layered Structures: Controlling Coupling with Covalent-Bond Organic Linkers

The Journal of Physical Chemistry C

A home-built ultrafast transient absorption setup was used in measurements, as detailed here: an ... more A home-built ultrafast transient absorption setup was used in measurements, as detailed here: an amplified, Fourier limited compressed pulses were used to feed the setup (4mJ, 35fs pulses, around central wavelength of 800nm, at a repetition rate of 1kHz). The beam was split in two to generate a 400nm pump using a frequency-doubling crystal (BBO), and a white-light supercontinuum probe, by focusing it onto a 3mm thick sapphire plate. Pump pulses were attenuated to intensities of few µJ/cm 2 at the sample plane, to achieve an average excitation per QD of ~0.02 1 ex N <<. Pump beam was chopped at half of the working frequency (i.e., 500Hz) to create pumpprobe-probe sequences, with temporal separation between pump and probe pulses controlled by a motorized delay line. Absorption difference between pumped and unpumped state of the sample were measured at a selected probe wavelength. Time resolution of the experiment, as determined from pump-probe intensity correlation is around 150fs.

Research paper thumbnail of Simple fabrication of SWIR detectors based on wet deposition of carbon nanotubes and quantum dots

Sensors and Actuators A: Physical

Research paper thumbnail of Optical Chiral Induced Spin Selectivity XMCD Study

CHIMIA International Journal for Chemistry

Research paper thumbnail of Marine Cyanobacteria Tune Energy Transfer Efficiency in their Light-harvesting Antennae by Modifying Pigment Coupling

Photosynthetic organisms regulate energy transfer to fit to changes in environmental conditions. ... more Photosynthetic organisms regulate energy transfer to fit to changes in environmental conditions. The biophysical principles underlying the flexibility and efficiency of energy transfer in the light-harvesting process are still not fully understood. Here we examine how energy transfer is regulated in-vivo. We compare different acclimation states of the photosynthetic apparatus in a marine cyanobacterial species that is well adapted to vertical mixing of the ocean water column and identify a novel acclimation strategy for photosynthetic life under low light intensities. Antennae rods extend, as expected, increasing light absorption. Surprisingly, in contrast to what was known for plants and predicted by classic calculations, these longer rods transfer energy faster i.e. more efficiently. The fluorescence lifetime and emission spectra dependence on temperature, at the range of 4-300K, suggests that energy transfer efficiency is tuned by modifying the energetic coupling strength between...

Research paper thumbnail of Unconventional order parameter induced by helical chiral molecules adsorbed on a metal proximity coupled to a superconductor

Physical Review B

Following our previous results, which provide evidence for the emergence of a chiral p-wave tripl... more Following our previous results, which provide evidence for the emergence of a chiral p-wave triplet-pairing component in superconducting Nb upon the adsorption of chiral molecules, we turned to investigate whether such an effect can take place in a proximal superconductor consisting of metal on superconductor bilayer. Note that in such proximity systems, correlated electron-hole (Andreev) pairs exist in the normal metal rather than genuine Cooper pairs. To that end, we used scanning tunneling spectroscopy (STS) on thin Au films grown in-situ on NbN (a conventional s-wave superconductor) before and after adsorbing helical chiral, alpha-helix polyalanine molecules. The tunneling spectra measured on the pristine Au surface showed conventional (swave like) proximity gaps. However, upon molecules adsorption the spectra significantly changed, all exhibiting a zero-bias conductance peak embedded inside a gap, indicating unconventional superconductivity. The peak reduced with magnetic field but did not split, consistent with equal-spin triplet-pairing p-wave symmetry. In contrast, adsorption of nonhelical chiral cysteine molecules did not yield any apparent change in the order parameter, and the tunneling spectra exhibited only gaps free of in-gap structure.