May 2023 • ACS Applied Nano Materials
Abderrahim Moumen, Rajashree Konar, Dario Zappa, Eti Teblum, Gilbert Daniel Nessim, Elisabetta Comini
Two-dimensional (2D) semiconducting heterojunction chemical sensors are in high demand because of their enhanced response, stability, and selectivity. However, fine-tuning heterojunctions using vapor deposition growth still needs further research. Our present study focuses on the ambient pressure chemical vapor deposition (CVD) synthesis of hexagonal tungsten sulfide-tungsten selenide (WS2–WSe2) p–p heterojunctions (as a 2D–2D arrangement). We use the liquid-phase exfoliation method to disperse bulk WS2 and WSe2 and decorate large flakes of WS2 with smaller WSe2 nanosheets in CVD. Electron microscopy and related surface investigations reveal their homogeneity on drop-casting. Two drops from the exfoliated heterojunction dispersion were drop-cast on a transducer to study the NO2 response and related sensing properties. The sensor showed long-term stability (>2 months), even at high …
Show moreMay 2023 • ACS Energy Letters
Pallavi Singh, Yahel Soffer, Davide Raffaele Ceratti, Michael Elbaum, Dan Oron, Gary Hodes, David Cahen
In terms of sustainable use, halide perovskite (HaP) semiconductors have a strong advantage over most other classes of materials for (opto)electronics, as they can self-heal (SH) from photodamage. While there is considerable literature on SH in devices, where it may not be clear exactly where damage and SH occur, there is much less on the HaP material itself. Here we perform “fluorescence recovery after photobleaching” (FRAP) measurements to study SH on polycrystalline thin films for which encapsulation is critical to achieving complete and fast self-healing. We compare SH in three photoactive APbI3 perovskite films by varying the A-site cation ranging from (relatively) small inorganic Cs through medium-sized MA to large FA (the last two are organic cations). While the A cation is often considered electronically relatively inactive, it significantly affects both SH kinetics and the threshold for photodamage. The …
Show moreMay 2023 • CLEO: Applications and Technology, AM4Q. 7, 2023
A Ben Yehuda, O Sefi, E Cohen, S Shwartz
We demonstrate ghost imaging with scattered x-ray radiation for the first time and show that its spatial resolution is significantly higher than the resolution of standard present-day methods that rely on x-ray scattering.
Show moreMay 2023 • arXiv e-prints
Naga Prathibha Jasti, Igal Levine, Yishay Feldman, Sigalit Aharon, David Cahen
The term defect tolerance (DT) is used often to rationalize the exceptional optoelectronic properties of Halide Perovskites, HaPs, and their devices. Even though DT lacked direct experimental evidence, it became fact in the field. DT in semiconductors implies tolerance to structural defects without the electrical and optical effects (eg, traps), associated with such defects. We present first direct experimental evidence for DT in Pb HaPs by comparing the structural quality of 2D, 2D_3D, and 3D Pb HaP crystals with their optoelectronic characteristics using high sensitivity methods. Importantly, we get information from the material bulk, because we sample at least a few 100 nm, up to several micrometer, from the sample surface, which allows assessing intrinsic bulk (and not only surface) properties of HaPs. The results point to DT in 3D, to a lesser extent in 2D_3D, but not in 2D Pb HaPs. We ascribe such dimension …
Show moreMay 2023 • PNAS Nexus
Ryo Okamoto, Eliahu Cohen
In quantum mechanics, a quantum system is irreversibly collapsed by a projective measurement. Hence, delicately probing the time evolution of a quantum system holds the key to understanding curious phenomena. Here we experimentally explore an anomalous time evolution, where, illustratively, a particle disappears from a box and emerges in a different box, with a certain moment in which it can be found in neither of them. In this experiment, we directly probe this curious time evolution of a single photon by measuring up to triple-operator sequential weak values using a novel probeless scheme. The naive interpretation provided by single-operator weak values seems to imply the “disappearance” and “re-appearance” of a photon as theoretically predicted. However, double- and triple-operator sequential weak values, representing temporal correlations between the aforementioned values, show that spatial …
Show moreMay 2023 • Colloids and Surfaces B: Biointerfaces
Raz Cohen, Karthik Ananth Mani, Madina Primatova, Gila Jacobi, Einat Zelinger, Eduard Belausov, Elazar Fallik, Ehud Banin, Guy Mechrez
This study reports significant steps toward developing anti-biofilm surfaces based on superhydrophobic properties that meet the complex demands of today's food and medical regulations. It presents inverse Pickering emulsions of water in dimethyl carbonate (DMC) stabilized by hydrophobic silica (R202) as a possible food-grade coating formulation and describes its significant passive anti-biofilm properties. The final coatings are formed by applying the emulsions on the target surface, followed by evaporation to form a rough layer. Analysis shows that the final coatings exhibited a Contact Angle (CA) of up to 155° and a Roll-off Angle (RA) lower than 1° on the polypropylene (PP) surface, along with a relatively high light transition. Dissolving polycaprolactone (PCL) into the continuous phase enhanced the average CA and coating uniformity but hindered the anti-biofilm activity and light transmission. Scanning …
Show moreMay 2023 • ACS Applied Materials & Interfaces
Sujit Kumar, Vinayaka H Damle, Tatyana Bendikov, Anat Itzhak, Michael Elbaum, Katya Rechav, Lothar Houben, Yaakov Tischler, David Cahen
Two-dimensional (2D) halide perovskites, HaPs, can provide chemical stability to three-dimensional (3D) HaP surfaces, protecting them from exposure to ambient species and from reacting with contacting layers. Both actions occur with 2D HaPs, with the general stoichiometry R2PbI4 (R: long or bulky organic amine) covering the 3D ones. Adding such covering films can also boost power conversion efficiencies of photovoltaic cells by passivating surface/interface trap states. For maximum benefit, we need conformal ultrathin and phase-pure (n = 1) 2D layers to enable efficient tunneling of photogenerated charge carriers through the 2D film barrier. Conformal coverage of ultrathin (<10 nm) R2PbI4 layers on 3D perovskites is challenging with spin coating; even more so is its upscaling for larger-area devices. We report on vapor-phase cation exchange of the 3D surface with the R2PbI4 molecules and real-time in situ …
Show moreMay 2023 • arXiv preprint arXiv:2305.04888
Udit Khanna, Ke Huang, Ganpathy Murthy, HA Fertig, Kenji Watanabe, Takashi Taniguchi, Jun Zhu, Efrat Shimshoni
Bilayer graphene exhibits a rich phase diagram in the quantum Hall regime, arising from a multitude of internal degrees of freedom, including spin, valley, and orbital indices. The variety of fractional quantum Hall states between filling factors suggests, among other things, a quantum phase transition between valley-unpolarized and polarized states at a perpendicular electric field . We find the behavior of with changes markedly as is reduced. At , may even vanish when is sufficiently small. We present a theoretical model for lattice-scale interactions which explains these observations; surprisingly, both repulsive and attractive components in the interactions are required. Within this model we analyze the nature of the state as a function of the magnetic and electric fields, and predict that valley-coherence may emerge for in the high regime. This suggests the system supports Kekule bond-ordering, which could in principle be verified via STM measurements.
Show moreMay 2023 • 243rd ECS Meeting with the 18th International Symposium on Solid Oxide Fuel Cells (SOFC-XVIII)
Lior Elbaz, Oran Lori
May 2023 • Scientific Reports
Bhupesh Kumar, Ran Homri, Patrick Sebbah
A two-dimensional (2D) solid-state random laser emitting in the visible is demonstrated, in which optical feedback is provided by a controlled disordered arrangement of air-holes in a dye-doped polymer film. We find an optimal scatterer density for which threshold is minimum and scattering is the strongest. We show that the laser emission can be red-shifted by either decreasing scatterer density or increasing pump area. We show that spatial coherence is easily controlled by varying pump area. Such a 2D random laser provides with a compact on-chip tunable laser source and a unique platform to explore non-Hermitian photonics in the visible.
Show moreMay 2023 • 2023 IEEE International Magnetic Conference-Short Papers (INTERMAG Short …, 2023
Hariharan Nhalil, Moty Schultz, Shai Amrusi, Asaf Grosz, Lior Klein
We present a miniature, ultra-sensitive magnetic field gradiometer in the form of a single elliptical planar Hall effect sensor that allows measuring magnetic field at 9 different locations on a 4 mm length scale [1]. The gradiometer detects magnetic field gradients with equivalent gradient magnetic noise levels of , and Hz at 0.1, 1, 10, and 50 Hz, respectively, and tested under ambient conditions by measuring the field gradient produced by an electric current flowing through a straight wire. The compact size, low noise level, versatility, simple design, and low cost of this gradiometer makes it a suitable choice for detecting magnetic field gradients in small, confined spaces such as current probes or wearable electronic medical devices.
Show moreMay 2023 • ACS Applied Nano Materials
Abderrahim Moumen, Rajashree Konar, Dario Zappa, Eti Teblum, Gilbert Daniel Nessim, Elisabetta Comini
Two-dimensional (2D) semiconducting heterojunction chemical sensors are in high demand because of their enhanced response, stability, and selectivity. However, fine-tuning heterojunctions using vapor deposition growth still needs further research. Our present study focuses on the ambient pressure chemical vapor deposition (CVD) synthesis of hexagonal tungsten sulfide-tungsten selenide (WS2–WSe2) p–p heterojunctions (as a 2D–2D arrangement). We use the liquid-phase exfoliation method to disperse bulk WS2 and WSe2 and decorate large flakes of WS2 with smaller WSe2 nanosheets in CVD. Electron microscopy and related surface investigations reveal their homogeneity on drop-casting. Two drops from the exfoliated heterojunction dispersion were drop-cast on a transducer to study the NO2 response and related sensing properties. The sensor showed long-term stability (>2 months), even at high …
Show moreMay 2023 • Applied Physics Letters
Amreen Bano, Dan Thomas Major
Spin–orbit coupling (SOC) combined with broken inversion symmetry plays a key role in inducing Rashba effect. The combined spontaneous polarization and Rashba effect enables controlling a material's spin degrees of freedom electrically. In this work, we investigated an electronic band structure for several combinations of TiX 2 monolayers (X= Te, S, and Se): TiTe 2/TiSe 2, TiTe 2/TiS 2, and TiSe 2/TiS 2. Based on the observed orbital hybridization between the different monolayers in these heterostructures (HSs), we conclude that the most significant Rashba splitting occurs in TiSe 2/TiS 2. Subsequently, we used fluorine (F) as an adatom over the surface of TiSe 2/TiS 2 at hollow and top sites of the surface to enhance the Rashba intensity, as the F adatom induces polarization due to the difference in charge distribution. Furthermore, by increasing the number of F atoms on the surface, we reinforced the band …
Show moreMay 2023 • Physical Review Research
Quancheng Liu, David A Kessler, Eli Barkai
Quantum walks underlie an important class of quantum computing algorithms, and represent promising approaches in various simulations and practical applications. Here we design stroboscopically monitored quantum walks and their subsequent graphs that can naturally boost target searches. We show how to construct walks with the property that all the eigenvalues of the non-Hermitian survival operator, describing the mixed effects of unitary dynamics and the back-action of measurement, coalesce to zero, corresponding to an exceptional point whose degree is the size of the system. Generally, the resulting search is guaranteed to succeed in a bounded time for any initial condition, which is faster than classical random walks or quantum walks on typical graphs. We then show how this efficient quantum search is related to a quantized topological winding number and further discuss the connection of the problem …
Show moreMay 2023 • Journal of Biomedical Optics
Gilad Yahav, Shweta Pawar, Yitzchak Weber, Bar Atuar, Hamootal Duadi, Dror Fixler
SignificanceWide-field measurements of time-resolved fluorescence anisotropy (TR-FA) provide pixel-by-pixel information about the rotational mobility of fluorophores, reflecting changes in the local microviscosity and other factors influencing the fluorophore’s diffusional motion. These features offer promising potential in many research fields, including cellular imaging and biochemical sensing, as demonstrated by previous works. Nevertheless, θ imaging is still rarely investigated in general and in carbon dots (CDs) in particular.AimTo extend existing frequency domain (FD) fluorescence lifetime (FLT) imaging microscopy (FLIM) to FD TR-FA imaging (TR-FAIM), which produces visual maps of the FLT and θ, together with the steady-state images of fluorescence intensity (FI) and FA (r).
Show moreMay 2023 • Journal of Applied Physics
Hariharan Nhalil, Moty Schultz, Shai Amrusi, Asaf Grosz, Lior Klein
We introduce a planar Hall effect magnetometer in the form of a parallel array of permalloy-based elliptical sensors. The number of ellipses in the array and other fabrication parameters are optimized with the support of numerical simulations. We obtain equivalent magnetic noise (EMN) of 16 pT/ffiffiffiffiffiffi Hz p at 100 Hz, 25 pT/ffiffiffiffiffiffi Hz p at 10 Hz, 98 pT/ffiffiffiffiffiffi Hz p at 1 Hz, and 470 pT/ffiffiffiffiffiffi Hz p at 0.1 Hz. The exceptional EMN without the use of magnetic flux concentrators highlights the advantages of the design. The presented magnetometer, characterized by its simplicity, affordability, and ability to operate at room temperature, is anticipated to be useful for applications requiring pT resolution.
Show moreMay 2023 • CLEO: Applications and Technology, AM4Q. 7, 2023
A Ben Yehuda, O Sefi, E Cohen, S Shwartz
We demonstrate ghost imaging with scattered x-ray radiation for the first time and show that its spatial resolution is significantly higher than the resolution of standard present-day methods that rely on x-ray scattering.
Show moreMay 2023 • ACS applied materials & interfaces
Sujit Kumar, Vinayaka H Damle, Tatyana Bendikov, Anat Itzhak, Michael Elbaum, Katya Rechav, Lothar Houben, Yaakov Tischler, David Cahen
Two-dimensional (2D) halide perovskites, HaPs, can provide chemical stability to three-dimensional (3D) HaP surfaces, protecting them from exposure to ambient species and from reacting with contacting layers. Both actions occur with 2D HaPs, with the general stoichiometry R2PbI4 (R: long or bulky organic amine) covering the 3D ones. Adding such covering films can also boost power conversion efficiencies of photovoltaic cells by passivating surface/interface trap states. For maximum benefit, we need conformal ultrathin and phase-pure (n = 1) 2D layers to enable efficient tunneling of photogenerated charge carriers through the 2D film barrier. Conformal coverage of ultrathin (<10 nm) R2PbI4 layers on 3D perovskites is challenging with spin coating; even more so is its upscaling for larger-area devices. We report on vapor-phase cation exchange of the 3D surface with the R2PbI4 molecules and real-time in situ …
Show moreMay 2023 • ACS ES&T Engineering
Belal Abu Salha, Arumugam Saravanan, Moorthy Maruthapandi, Ilana Perelshtein, Aharon Gedanken
Plant-derived carbon dots have superior light absorption and intrinsic fluorescence properties. In this work, we have prepared nitrogen-doped carbon dots (N-CDs) from Piper betle leaves using a simple hydrothermal method. The synthesized N-CDs were characterized by various techniques such as high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared, and photoluminescence. The N-CDs further proved to have systemic effects on the growth of strawberries compared with irrigating the strawberry plants with water and regular nutrients. The strawberry plants treated with N-CDs exhibited an increase in chlorophyll content of about 24.7%, which was reflected in increased carbohydrate content of approximately 48.61% compared to control plants. Also, N-CD-treated strawberry plants showed increased secondary metabolites (phenolics) compared to control …
Show moreMay 2023 • arXiv preprint arXiv:2205.08563
Hennadii Yerzhakov, Roni Ilan, Efrat Shimshoni, Jonathan Ruhman
Topological superconductors are predicted to exhibit outstanding phenomena, including non-abelian anyon excitations, heat-carrying edge states, and topological nodes in the Bogoliubov spectra. Nonetheless, and despite major experimental efforts, we are still lacking unambiguous signatures of such exotic phenomena. In this context, the recent discovery of coexisting superconductivity and ferroelectricity in lightly doped and ultra clean SrTiO opens new opportunities. Indeed, a promising route to engineer topological superconductivity is the combination of strong spin-orbit coupling and inversion-symmetry breaking. Here we study a three-dimensional parabolic band minimum with Rashba spin-orbit coupling, whose axis is aligned by the direction of a ferroelectric moment. We show that all of the aforementioned phenomena naturally emerge in this model when a magnetic field is applied. Above a critical Zeeman field, Majorana-Weyl cones emerge regardless of the electronic density. These cones manifest themselves as Majorana arcs states appearing on surfaces and tetragonal domain walls. Rotating the magnetic field with respect to the direction of the ferroelectric moment tilts the Majorana-Weyl cones, eventually driving them into the type-II state with Bogoliubov Fermi surfaces. We then consider the consequences of the orbital magnetic field. First, the single vortex is found to be surrounded by a topological halo, and is characterized by two Majorana zero modes: One localized in the vortex core and the other on the boundary of the topological halo. For a finite density of vortices forming close enough to the upper critical field, these halos …
Show moreMay 2023 • Journal of Functional Biomaterials
Elisheva Sasson, Omer Agazani, Eyal Malka, Meital Reches, Shlomo Margel
In March 2020, the World Health Organization announced a pandemic attributed to SARS-CoV-2, a novel beta-coronavirus, which spread widely from China. As a result, the need for antiviral surfaces has increased significantly. Here, the preparation and characterization of new antiviral coatings on polycarbonate (PC) for controlled release of activated chlorine (Cl+) and thymol separately and combined are described. Thin coatings were prepared by polymerization of 1-[3-(trimethoxysilyl)propyl] urea (TMSPU) in ethanol/water basic solution by modified Stöber polymerization, followed by spreading the formed dispersion onto surface-oxidized PC film using a Mayer rod with appropriate thickness. Activated Cl-releasing coating was prepared by chlorination of the PC/SiO2-urea film with NaOCl through the urea amide groups to form a Cl-amine derivatized coating. Thymol releasing coating was prepared by linking thymol to TMSPU or its polymer via hydrogen bonds between thymol hydroxyl and urea amide groups. The activity towards T4 bacteriophage and canine coronavirus (CCV) was measured. PC/SiO2-urea-thymol enhanced bacteriophage persistence, while PC/SiO2-urea-Cl reduced its amount by 84%. Temperature-dependent release is presented. Surprisingly, the combination of thymol and chlorine had an improved antiviral activity, reducing the amount of both viruses by four orders of magnitude, indicating synergistic activity. For CCV, coating with only thymol was inactive, while SiO2-urea-Cl reduced it below a detectable level.
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