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- 摘要
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- 实验方案
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Synthesis, chemical, theoretical studies, electrochemical, electrical and optical characterization of novel oligomer 2,2’-((1E,1’E)(2,5-bis(octyloxy)-1,4-phenylenevinylene)bis(6-(E)-2-(vinylquinolin))quinoline for OLED applications
摘要： A fluorescent pentamer 5QnQnPV with one phenyl central donor group surrounded by four quinoline acceptor groups set in a quadrupolar A-π-A-π-D-π-A-π-A electronic structure was synthesized. This compound is an organic semiconductor and shows a wide band fluorescence emission that spans from the blue to the red region with a maximum peak centered at 509 nm. In addition, its HOMO (? 5.4 eV)/LUMO (? 3.5 eV) energy values, determined by cyclic voltammetry, optical gap EgOpt of 2.18 and theoretical DT-DFT studies indicated a potential for OLED fabrication. When such device was made with a ITO/PEDOT:PSS/5QnQnPV/Al configuration it displayed a maximum electroluminescent response at 860 nm. The structural and physical characterization of this compound was performed using 1H and 13C Nuclear Magnetic Resonance, Fourier Transformed Infrared Spectroscopy, Mass Spectroscopy and Atomic Force Microscopy.
关键词： organic semiconductor,Atomic Force Microscopy,Fourier Transformed Infrared Spectroscopy,Mass Spectroscopy,electroluminescent response,fluorescent pentamer,Nuclear Magnetic Resonance,OLED
更新于2025-09-11 14:15:04
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Enhancement of cell differentiation on a surface potential-controlled nitrogen-doped TiO<sub>2</sub> surface
摘要： MC3T3-E1 cell differentiation is more pronounced after 14 days incubation on charged nitrogen-doped TiO2 surfaces compared to on an untreated, neutral Ti surface. The protein fibronectin (Fn) was detected by an immunogold-labeling technique and Ca and P were detected by time-of-flight secondary ion mass spectrometry. Both techniques revealed that an adhesive protein such as Fn adsorbs equally on negatively-charged, positively-charged, and untreated Ti surfaces in culture medium. However, the adsorption of Ca and P was only detected on charged nitrogen-doped TiO2 surfaces. The enhanced adsorption of inorganic ions and Fn is probably responsible for promoting initial stage of osteoblast differentiation. The conformation of adsorbed Fn was observed by high-speed atomic force microscopy and found to be in the side-on orientation on the positively-charged surface. This finding may help elucidate the relation between Fn conformation and cell activity on surface potential-controlled nitrogen-doped TiO2 surfaces in future.
关键词： TiO2 surface,High-speed atomic force microscopy,Cellular response,Immunogold-labeling technique,Fibronectin,Surface potential
更新于2025-09-11 14:15:04
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Epitaxy || Epitaxy and Device Properties of InGaAs Photodetectors with Relatively High Lattice Mismatch
摘要： In this chapter, our works on the developments of wavelength-extended InGaAs photodetectors with cutoff wavelength >1.7 μm are reviewed. Various InGaAs/InAlAs p-i-n heterojunction structures have been grown on InP and GaAs substrates by gas source molecular beam epitaxy, some details on the InGaAs photodetector structures and the techniques of metamorphic buffer layer such as linearly, step, and one-step continuously InAlAs graded buffer, and dislocation restraint methods of compositional overshoot and digital alloy are introduced. The material characteristics and device properties were evaluated by atomic force microscopy, high-resolution X-ray diffraction and reciprocal space mapping, cross-sectional transmission electron microscopy, and current-voltage measurements, etc. The results provide clues to the development of metamorphic device structures on lattice-mismatched material systems.
关键词： photodetector,X-ray diffraction,InGaAs,metamorphic,atomic force microscopy,photoluminescence,lattice mismatch
更新于2025-09-11 14:15:04
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Vacuum-UV of polyetheretherketone (PEEK) as a surface pre-treatment for structural adhesive bonding
摘要： Polyetheretherketone (PEEK) is known for its poor wettability and poor adhesive properties. Hence, for the creation of reliable high-strength structural adhesive bonded joints, surface treatment of PEEK is required. In this work high strength bondable PEEK surfaces were achieved through a vacuum-UV (VUV) treatment. Samples of amorphous and semi-crystalline PEEK films were exposed to different VUV radiation doses. Additionally oxygen low-pressure plasma (LPP) and untreated (as received) PEEK samples were investigated for comparison. Surfaces were characterized using x-ray photoelectron spectroscopy (XPS), contact angle measurements (CA), atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). Tensile tests of the PEEK films were carried out, to investigate changes in the mechanical properties in the bulk of the PEEK films due to the VUV exposure. The adhesive bond strength of treated specimen was determined through two different test methods (tensile and shear). These strengths were compared to the created surface properties. A strong correlation between the contact angle and the creation of functional groups was observed. VUV radiation appears as a suitable pre-treatment method for PEEK, as adhesive bonds of high strength were achieved after 5 seconds. Additionally, the usage of a VUV excimer lamp is simple, cheap and easy for automation.
关键词： X-ray photoelectron spectroscopy,Vacuum-UV (VUV),contact angles,chemical surface functionalization,structural adhesive bonding,Polyetheretherketone (PEEK),atomic force microscopy
更新于2025-09-11 14:12:44
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Quantitative comparison of wideband low-latency phase-locked loop circuit designs for high-speed frequency modulation atomic force microscopy
摘要： A phase-locked loop (PLL) circuit is the central component of frequency modulation atomic force microscopy (FM-AFM). However, its response speed is often insufficient, and limits the FM-AFM imaging speed. To overcome this issue, we propose a PLL design that enables high-speed FM-AFM. We discuss the main problems with the conventional PLL design and their possible solutions. In the conventional design, a low-pass filter with relatively high latency is used in the phase feedback loop, leading to a slow response of the PLL. In the proposed design, a phase detector with a low-latency high-pass filter is located outside the phase feedback loop, while a subtraction-based phase comparator with negligible latency is located inside the loop. This design minimizes the latency within the phase feedback loop and significantly improves the PLL response speed. In addition, we implemented PLLs with the conventional and proposed designs in the same field programmable gate array chip and quantitatively compared their performances. The results demonstrate that the performance of the proposed PLL is superior to that of the conventional PLL: 165 kHz bandwidth and 3.2 μs latency in water. Using this setup, we performed FM-AFM imaging of calcite dissolution in water at 0.5 s/frame with true atomic resolution. The high-speed and high-resolution imaging capabilities of the proposed design will enable a wide range of studies to be conducted on various atomic-scale dynamic phenomena at solid–liquid interfaces.
关键词： frequency modulation atomic force microscopy,high-speed atomic-resolution imaging,phase-locked loop,calcite dissolution process
更新于2025-09-10 09:29:36
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Thermal Atomic Layer Etching of Silicon Using O2, HF and Al(CH3)3 as the Reactants
摘要： The thermal atomic layer etching (ALE) of silicon was performed using O2, HF and Al(CH3)3 as the reactants at temperatures from 225-290°C. This thermal etching process is based on Si oxidation using O2 and conversion of SiO2 to Al2O3 using trimethylaluminum (TMA). Al2O3 is then fluorinated by HF to produce AlF3 prior to removal of AlF3 by a ligand-exchange reaction with TMA. Thermal Si ALE was studied using silicon-on-insulator (SOI) wafers. In situ spectroscopic ellipsometry was employed to monitor simultaneously both the thickness of the top SiO2 layer and the underlying silicon film during Si ALE. These studies observed that the silicon film thickness decreased linearly with the number of reaction cycles while the thickness of the SiO2 layer remained constant. Using an O2-HF-TMA exposure sequence, the Si ALE etch rate was 0.4 ?/cycle at 290°C. This etch rate was obtained using static reactant pressures of 250, 1.0 and 1.0 Torr, and exposure times of 10, 5 and 5 s, for O2, HF and TMA, respectively. The SiO2 thickness was 10-11 ? under these reaction conditions at 290°C. The Si ALE etch rate increased with O2 and TMA pressure before reaching a limiting etch rate at higher O2 and TMA pressures. The order of the reactants affected the Si etch rate. Changing the exposure sequence from O2-HF-TMA to O2-TMA-HF reduced the etch rate from 0.4 to 0.2 ?/cycle at 290°C. Lowering the etch temperature below 290oC also resulted in the reduction of the Si etch rate. Atomic force microscopy (AFM) measurements determined that the root-mean-squared (RMS) roughness of the surface was 2.0 ± 0.2 ? before and after the Si ALE using the optimum reaction conditions. Lowering the static O2 pressures below 250 Torr reduced the etch rate and also increased the RMS surface roughness. There was no evidence for any change in the Si ALE process for ultrathin Si films with thicknesses <100 ? in the quantum confinement regime. Thermal Si ALE should be useful for silicon applications in many areas including electronics, optoelectronics, thermoelectrics and photonics.
关键词： silicon,HF,thermal atomic layer etching,spectroscopic ellipsometry,Al(CH3)3,O2,atomic force microscopy
更新于2025-09-10 09:29:36
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High-Yield Formation of Graphdiyne Macrocycles Through On-Surface Assembling and Coupling Reaction
摘要： Rationally designed halogenated hydrocarbons are widely used building blocks to fabricate covalent-bonded carbon nanostructures on surface through a reaction pathway involving generation and dissociation of organometallic intermediates and irreversible covalent bond formation. Here we provide a comprehensive picture of the on-surface-assisted homocoupling reaction of 1,3-bis(2-bromoethynyl)benzene on Au(111), aiming for the synthesis of graphdiyne nanostructures. Submolecular resolution scanning tunneling microscopy and noncontact atomic force microscopy observations identify the organometallic intermediates and their self-assemblies formed in the dehalogenation process. The demetallization of the organometallic intermediates at elevated temperatures produces butadiyne moieties that spontaneously formed two different covalent structures, i.e. graphdiyne zigzag chains and macrocycles, whose ratio was found to depend on the initial coverage of organometallic intermediates. At the optimal condition, the stepwise demetallization and cyclization led to a high yield production of graphdiyne macrocycles up to 95 %. Statistical analysis and theoretical calculations suggested that the favored formation of macrocycles was resulted from the complex interplay between thermodynamic and kinetic processes involving the organometallic bonded intermediates and the covalently bonded butadiyne moieties.
关键词： on-surface reaction,graphdiyne macrocycle,organometallic intermediate,scanning tunneling microscopy,noncontact atomic force microscopy,thermodynamic and kinetic control
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Accurate Measurement at the Nanoscale of Remnant Polarisation Charge in Ferroelectric Films
摘要： A method for the measurement of the remnant polarisation charge of ferroelectric ?lms at the nanoscale is proposed. It is based on current measurement by an atomic force microscope and imposes a capacitive correction in order to extract the signal from the noise, several orders of magnitude higher than the signal to be measured. A remnant charge of 4.2 fC could be measured on a PbZrTiO3 thin ?lm. Solutions to decrease the noise are proposed.
关键词： ferroelectric materials,remnant polarisation,nanoscale current measurement,Atomic Force Microscopy
更新于2025-09-10 09:29:36
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Can a new microscopy platform help to improve clinical outcomes?
摘要： Next-generation sequencing (NGS), also referred to as ‘second-generation sequencing’, ushered in an era of plummeting sequencing costs that has enabled rapid progress in the research of genetic diversity, variants, transcription and epigenetics, among other fields. In the clinical sphere, NGS spurred the dream of precision medicine (PM) or personalized medicine, in which the genome of each patient (or pre-patient) is sequenced, and an optimal treatment is designed based on one’s genetic code, lifestyle and environment. Despite these gains and hopes, NGS is limited by its short-read approach and per-patient cost, and PM has yet to exhibit transformative reach, with only a small proportion of US patients currently receiving genome-informed therapy. In order for PM to become a standard of care, there is an urgent need for fast, cheap and reliable genetic diagnostics to complement existing techniques. We offer a novel high-speed atomic force microscopy ‘nanomapping’ platform to help meet the challenge.
关键词： nanotechnology,atomic force microscopy,DNA sequencing,genomics
更新于2025-09-10 09:29:36
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Nanoimaging of food proteins by atomic force microscopy. Part I: Components, imaging modes, observation ways, and research types
摘要： AFM has become an important nanotech tool to analyze proteins and many food scientists have used it to analyze food proteins in the past three decades. This review focuses on the application of AFM nanoimaging and contains two parts. In this part I, the AFM components, imaging modes, observation ways, and research types according to different research needs are reviewed and discussed in this part I. The advantages and disadvantages of AFM for food protein nanoimaging are also discussed. The part I of this review provides comprehensive technical information of AFM nanoimaging for food proteins.
关键词： operational mode,atomic force microscopy,nanoimaging,food protein,research types
更新于2025-09-10 09:29:36