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Preparation of erythromycin imprinted polymer by metal-free visible-light–induced ATRP and its application in sensor
摘要： Erythromycin (ERY) molecular imprinted polymer was prepared on the surface of Au electrode modified with Ni and Au nanoclusters (MIP/AuNCs/Ni/Au) via metal-free visible-light–induced atom transfer radical polymerization, which was very easy, controllable, and environmentally benign. MIP/AuNCs/Ni/Au was examined by energy dispersive spectrometer (EDS), scanning electron microscope (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Further, MIP/AuNCs/Ni/Au was successfully used for the determination of ERY by differential pulse voltammetry (DPV). Under the optimal conditions, MIP/AuNCs/Ni/Au gave a linear correlation over the ERY concentration from 1.0 × 10?8 to 1.0 × 10?1 mg/L with the detection limit of 3.2 × 10?9 mg/L (S/N = 3). Comparing with the similar sensors, the larger linear range and lower detection limit indicated the promising prospect of this electrochemical sensor. Hence, this study was of great importance for the polymer-modified electrodes and the sensitive detection of ERY.
关键词： Molecular imprinted polymer (MIP),Metal-free visible-light–induced atom transfer radical polymerization (MVL ATRP),Erythromycin (ERY)
更新于2025-09-04 15:30:14
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Preparation of Ag2Se QDs with excellent aqueous dispersion stability by organic coating with aqueous ATRP
摘要： In this article, water-dispersible Ag2Se quantum dots (QDs) were prepared by the facile and environmental-friendly method. In our approach, atom transfer radical polymerization (ATRP) was adopted in aqueous media to grow polymer chains from the surface of Ag2Se QDs. The aqueous ATRP allows the very mild synthetic conditions. In the present work, the polymerization reaction of methoxy[oligo(ethylene glycol)] methacrylate (OEGMA) was carried out at room temperature under aqueous conditions after the incorporation of 2-bromopropionyl moiety as the ATRP initiator on the surface of Ag2Se QDs by the ligand exchange method. OEGMA-coated Ag2Se QDs were successfully obtained without significant morphological change. The aqueous dispersion stability of OEGMA-coated Ag2Se QDs was compared with that of conventional water-dispersible Ag2Se QDs prepared by the simple modification with 11-mercaptoundecanoic acid. As a result, OEGMA-coated Ag2Se QDs showed the extremely high aqueous dispersion stability.
关键词： Aqueous dispersion stability,Methoxy[oligo(ethylene glycol)] methacrylate,Ag2Se quantum dot,Organic coating,Aqueous atom transfer radical polymerization
更新于2025-09-04 15:30:14
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Kinetic Study of Degrafting Poly(methyl methacrylate) Brushes from Flat Substrates by Tetrabutylammonium Fluoride
摘要： Polymer degrafting is a process in which surface-attached polymer brushes are removed from the substrate by breaking a chemical bond in proximity to the substrate. This paper provides insight into the kinetics of degrafting poly(methyl methacrylate) (PMMA) brushes using tetrabutylammonium fluoride (TBAF) and demonstrates how the process can be modeled using a series of degrafting reactions. The trichlorosilane-based polymerization initiator utilized here to synthesize PMMA grafts by surface-initiated atom transfer radical polymerization anchors to the silica substrate by up to three potential attachment points. During the degrafting sequence this anchoring reduces to two and one chemical bond and finally results in complete liberation of the PMMA macromolecule from the substrate. We investigate the effect of TBAF concentration, the initial grafting density of PMMA grafts on the substrate, and TBAF exposure time on degrafting of PMMA by monitoring the instantaneous areal grafting density of PMMA on the substrate.
关键词： PMMA brushes,Polymer degrafting,TBAF,kinetics,surface-initiated atom transfer radical polymerization
更新于2025-09-04 15:30:14
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Encyclopedia of Spectroscopy and Spectrometry || Ion Collision, Theory ☆
摘要： Collisions between an ion and neutral species result in a number of possible outcomes depending upon the chemical and physical properties of the two reactants, their relative velocities, and the impact parameter of their trajectories. These include elastic and inelastic scattering of the colliding particles, charge transfer (including dissociative charge transfer), atom abstraction, complex formation and dissociation of the colliding ion. Each of these reactions may be characterized in terms of their energy-dependent rate coefficients, cross sections and reaction kinetics. This article outlines a theoretical framework for discussing these processes that emphasizes simple models and classical mechanics. The discussion of collision processes has been divided into two categories: low-energy and high-energy thermal or quasi-thermal collisions. Experiments under conditions – swarms, drift tubes, chemical ionization and ion cyclotron resonance – are strongly influenced by long-range forces and often involve ‘capture collisions’ in which atom exchange and extensive energy exchange are common characteristics. High-energy collisions are typically impulsive, involve short-range intermolecular forces and are direct, fast processes.
关键词： Low-energy Collisions,Elastic and Inelastic Scattering,Reaction Kinetics,Theory,Complex Formation,Rate Coefficients,Charge Transfer,Atom Abstraction,High-energy Collisions,Ion Collision,Dissociation,Cross Sections
更新于2025-09-04 15:30:14
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[Advances In Atomic, Molecular, and Optical Physics] Volume 67 || Radio-Frequency Spectroscopy as a Tool for Studying Coherent Spin Dynamics and for Application to Radio-Frequency Magnetometry
摘要： The technique of radio-frequency spectroscopy was introduced more than 50 years ago, but is continuing to evolve and is being used as an ever-more versatile tool. We describe the underlying processes that govern the various contributions to the spectroscopic signals, considering the atom-light couplings. We then apply this understanding to demonstrate how the coherent dynamics can be manipulated with different configurations of optical pumping. Finally, we discuss how to implement rf spectroscopy to give optimized sensitivity in atomic magnetometers.
关键词： radio-frequency spectroscopy,atom-light couplings,atomic magnetometry,optical pumping,coherent spin dynamics
更新于2025-09-04 15:30:14
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Accurate semiempirical analytical formulas for spontaneous polarization by crystallographic parameters of SrTiO3-BaTiO3 system by ab initio calculations
摘要： Spontaneous polarizations (PS’s) of BaTiO3 and SrTiO3 under various conditions are calculated ab initio using different exchange-correlation functionals. The extensive theoretical sets of PS vs. ion positions are found to lie on a single curve, despite the chemical differences and the wide variations of PS and lattice parameters. This uncovers accurate simple analytical formulas of PS of SrTiO3-BaTiO3 system expressed by ion positions; a single formula predicts both macroscopic and atomic-scale PS of SrTiO3, BaTiO3 and SrTiO3-BaTiO alloys. The accuracy of the formula is demonstrated by the application to experiments, BaTiO3-SrTiO3 (-CaTiO3) alloys, Sr4Ti4O12 with PS // a-axis, a parallel domain, and a headon domain. In addition, the present results verify empirically that oxygen displacement is the primary identifier and the origin of PS of SrTiO3 and BaTiO3 and indicate that BaTiO3 and SrTiO3 may transforms into new state by an extremely large strain, e.g., ?3%. Furthermore, the earlier prediction of headon domain without aid of defects was confirmed. The present procedures for finding formulas can be applied to other materials.
关键词： Crystallographic estimation,Polarization,Strain,Atom position,Domain,TEM
更新于2025-09-04 15:30:14
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High-Fidelity Single-Qubit Gates on Neutral Atoms in a Two-Dimensional Magic-Intensity Optical Dipole Trap Array
摘要： As a conventional approach, optical dipole trap (ODT) arrays with linear polarization have been widely used to assemble neutral-atom qubits for building a quantum computer. However, due to the inherent scalar differential light shifts (DLS) of qubit states induced by trapping fields, the microwave-driven gates acting on single qubits suffer from errors on the order of 10?3. Here, we construct a DLS compensated ODT array based upon a recently developed magic-intensity trapping technique. In such a magic-intensity optical dipole trap (MI-ODT) array, the detrimental effects of DLS are efficiently mitigated so that the performance of global microwave-driven Clifford gates is significantly improved. Experimentally, we achieve an average error of e4.7 (cid:2) 1.1T × 10?5 per global gate, which is characterized by randomized benchmarking in a 4 × 4 MI-ODT array. Moreover, we experimentally study the correlation between the coherence time and gate errors in a single MI-ODT with an optimum error per gate of e3.0 (cid:2) 0.7T × 10?5. Our demonstration shows that MI-ODT array is a versatile platform for building scalable quantum computers with neutral atoms.
关键词： quantum computing,microwave-driven gates,optical dipole trap,magic-intensity trapping,neutral-atom qubits
更新于2025-09-04 15:30:14
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European Microscopy Congress 2016: Proceedings || Factors limiting the doping efficiency in atomic layer deposited ZnO:Al thin films: a dopant distribution study by transmission electron microscopy and atom probe tomography
摘要： Transparent conducting oxides (TCOs), such as indium tin oxide (ITO), are commonly used as transparent electrodes in a wide variety of devices, such as in displays and solar cells. ZnO has been reported to be a promising alternative TCO for ITO, because of its lower cost. As the conductivity of intrinsic ZnO films is too low for the applications in mind, doping the ZnO film is essential, the most common dopant being Al. Atomic layer deposition (ALD) is an emerging technique for the deposition of doped ZnO thin films, allowing for accurate thickness control and excellent conformality on high aspect ratio topologies. Due to the self-limiting half-reactions and cyclic nature of the ALD process, not only the aforementioned characteristics can be met, but also the amount and distribution of dopants can be controlled by selecting the precursors (i.e. the Zn or Al precursors) for each individual half-cycle. However, thus far, the maximum conductivity that can be obtained in Al-doped ZnO (ZnO:Al) thin films prepared by ALD appears to be limited by the low doping efficiency of Al. To better understand the origin of this limitation, the 3-dimensional distribution of Al atoms in ZnO films has been examined using a combination of Transmission Electron Microscopy (TEM) and Atom Probe Tomography (APT). For this study, three ZnO:Al films with different Al:Zn ratios were grown sequentially in one film stack, and capped and separated by intrinsic ZnO films. A diagram of the stack is shown in Fig. 1a. This geometry allowed a single APT or TEM measurement to collect data on all three doped films, keeping the analytical conditions identical. BFTEM studies (Fig 1b) showed that for high Al concentrations the ZnO grains are interrupted, while they continue across the lower doped layers. Scanning TEM – High Angle Annular Dark Field (HAADF) imaging and 2-D EDX mappings allows for revealing the aluminum distribution as a function of film depth, showing that the Al-doped layers follow the surface topography of the ZnO grains during growth Fig. 1c,d. However, TEM is limited in providing 3-D dopant distributions, on the one hand because of the limited sensitivity of EDX, on the other hand because of the projection of rough interfaces in a 2-D image. The latter is illustrated in Fig. 2a: individual Al-doped layers can clearly be discerned for larger interspacings, but are poorly recognizable in layer ‘AZO-3’. One-dimensional depth profiles extracted from cylindrical sub-volumes of the 3D APT data (Fig. 2 b) are presented in Fig. 2c. These 1D profiles show that the peaks in Al concentration are no δ-functions, as might be expected from the binary nature of the ALD process. Instead, the peaks have a full width at half maximum (FWHM) of ~2 nm. The 3-dimensional dopant distribution can be used to explain the dependencies of resistivity and doping efficiency on growth recipes used. When the local Al density is too high, the doping efficiency is limited by two proposed limiting factors: the solid solubility limit of Al atoms in a ZnO matrix and the disorder-induced carrier localization.
关键词： atom probe tomography,atomic layer deposition,transparent conducting oxides
更新于2025-09-04 15:30:14
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Following electron impact excitation of single(58Ce, 59Pr, 60Nd, 61Pm, 62Sm, 63Eu, 64Gd, 65Tb, 66Dy, 67Ho) atom M subhell ionization cross sections by using Lotz’s equations
摘要： M shell and M subshells ionization cross sections(σM) and σMi(i = 1,.,5) following electron impact on single(Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho)atoms calculated. By using Lotz's equation in Matlab σMand σMi cross section values obtained for 12 electron impact energies Eoi in EMi≤Eo<5EMi range for each atom. Lotz’s parameters and special commands used for each σMi calculations. Starting allmost from Eo = EMi values; σMi and σMi are increasing rapidly with Eo. For a fixed Eo ≈ 3.5EMi while Z value increases from 58≤Z≤67 σM and σMi decrease with Z. Results show that for Eovalues close to EMi values, characteristic x-ray yields formation of Mi(i = 1,.,5) subshells decreases while competing other events (Auger electrons, Coster-Kronig transitions) are increase. These results will also help to understand some results which obtained from other electron-atom impact studies on σMi subshells.
关键词： Electron impact on single atom,Near Mi subshells threshold energy region.,Mi subshells ionization cross sections of single Ce to Tb
更新于2025-09-04 15:30:14
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Entanglement between artificial atoms and photons of lossless cavities
摘要： We investigated the dynamics of atom-field entanglement for two natural or artificial two-level atoms interacting with a one-mode quantum electromagnetic field by means of multiphoton transitions in a lossless cavity. Tavis-Cummings model is used to describe the interaction of the atoms and real microwave coplanar cavity field. We carried out the mathematical modeling of the dynamics of the system under consideration for various initial states of the atomic subsystem and an intensive coherent field of the cavity. We showed that for small multiplicities, the atoms and the field, which were initially in a pure separable state, can return to this state during the evolution. We also found that for large multiplicities the atoms and the field are in the entangled atom-field state in the process of the system evolution with the exception of the initial time instant. These results can be used in the theory of quantum networks.
关键词： Tavis-Cummings model,multiphoton transitions,atom-field entanglement,quantum networks
更新于2025-09-04 15:30:14