- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Multimodal hard x-ray imaging with resolution approaching 10 nm for studies in material science
摘要： We report multimodal scanning hard x-ray imaging with spatial resolution approaching 10 nm and its application to contemporary studies in the field of material science. The high spatial resolution is achieved by focusing hard x-rays with two crossed multilayer Laue lenses and raster-scanning a sample with respect to the nanofocusing optics. Various techniques are used to characterize and verify the achieved focus size and imaging resolution. The multimodal imaging is realized by utilizing simultaneously absorption-, phase-, and fluorescence-contrast mechanisms. The combination of high spatial resolution and multimodal imaging enables a comprehensive study of a sample on a very fine length scale. In this work, the unique multimodal imaging capability was used to investigate a mixed ionic-electronic conducting ceramic-based membrane material employed in solid oxide fuel cells and membrane separations (compound of Ce0.8Gd0.2O2?x and CoFe2O4) which revealed the existence of an emergent material phase and quantified the chemical complexity at the nanoscale.
关键词： mixed ionic-electronic conducting membrane,x-ray nanoscale imaging,multimodal imaging,high spatial resolution
更新于2025-09-23 15:23:52
-
Intrinsic anion diffusivity in lead halide perovskites is facilitated by a soft lattice
摘要： Facile ionic transport in lead halide perovskites plays a critical role in device performance. Understanding the microscopic origins of high ionic conductivities has been complicated by indirect measurements and sample microstructural heterogeneities. Here, we report the direct visualization of halide anion interdiffusion in CsPbCl3–CsPbBr3 single crystalline perovskite nanowire heterojunctions using wide-field and confocal photoluminescence measurements. The combination of nanoscale imaging techniques with these single crystalline materials allows us to measure intrinsic anionic lattice diffusivities, free from complications of microscale inhomogeneity. Halide diffusivities were found to be between 10?13 and ～10?12 cm2/second at about 100 °C, which are several orders of magnitudes lower than those reported in polycrystalline thin films. Spatially resolved photoluminescence lifetimes and surface potential measurements provide evidence of the central role of halide vacancies in facilitating ionic diffusion. Vacancy formation free energies computed from molecular simulation are small due to the easily deformable perovskite lattice, accounting for the high equilibrium vacancy concentration. Furthermore, molecular simulations suggest that ionic motion is facilitated by low-frequency lattice modes, resulting in low activation barriers for vacancy-mediated transport. This work elucidates the intrinsic solid-state ion diffusion mechanisms in this class of semisoft materials and offers guidelines for engineering materials with long-term stability in functional devices.
关键词： anion diffusivity,nanoscale imaging,molecular simulation,halide perovskite nanowire,soft lattice
更新于2025-09-23 15:21:01
-
Reference Module in Materials Science and Materials Engineering || Tip-Enhanced Raman Microscopy: Instrumentation, Techniques and Applications in Practice
摘要： The idea of optical microscopy is to use a set of lenses to magnify the object to see. Scientists changed the idea of this conventional optical microscopy since the scanning probe microscope (SPM) came out in 1980s. Inouye and Kawata proposed to use a sharp metal probe to create an optical image [1]. They scanned the metal tip on a sample surface while recording the optical near-field signals scattered by the tip [1,2]. The spatial resolution is not determined by the numerical aperture (N.A.) of the objective lens but by the tip radius that is typically a few tens of nanometers. The use of a metal tip provides not only high spatial resolution but also an enhancement of optical signals as a result of excitation of surface plasmons at the sharp metal tip. With the tip-enhancement effect, it becomes possible to detect even a very weak optical signal scattered from an extremely tiny volume. One such process is Raman scattering. The application of tip-enhancement to Raman spectroscopy was reported in the year of 2000 by three independent groups led by Kawata, Zenobi, and Anderson, respectively [3–6]. Using TERS, distribution of molecules [7–11] and electronic [12] and chemical properties within nanoscale materials [13–18] have been successfully visualized through Raman signatures with a nanoscale spatial resolution. There are a number of review articles for TERS microscopy and spectroscopy available in literatures [14,19–22]. During the past 20 years, the development of TERS has been mostly driven by research labs having research-grade apparatus operated by skillful researchers. The situation has been changing in the recent years, some companies have started to sell commercial products of TERS microscopes in the market. However, in order to realize TERS microscope as an analytical tool for the routine use of research and industry, challenges in TERS probes, reproducibility issues remain such as stable implementation of atomic force microscopes (AFMs), and peripheral operational techniques.
关键词： Raman spectroscopy,nanoscale imaging,plasmonic enhancement,Tip-Enhanced Raman Microscopy,TERS
更新于2025-09-10 09:29:36
-
Atomic Force Microscopy in Molecular and Cell Biology || AFM and NSOM/QD Based Direct Molecular Visualization at the Single-Cell Level
摘要： Cell surface molecules such as receptors play an important role to regulate many essential cellular processes, including cell adhesion, tissue development, cellular communication, inflammation, tumor metastasis, and microbial infection. Specially, these events often involve multimolecular interactions occurring on a nanometer scale, and how to image the distribution and organization of cell surface molecules are becoming increasingly required in Cell and Molecular biology Sciences. By combing atomic force microscopy (AFM), near-field scanning microscopy (NSOM) and quantum dots (QD) labeling, a novel AFM and NSOM/QD-based dual-color nanoscale imaging system is constructed to directly visualize the distribution and organization of these molecules on cell-membrane surface. And this will supply a powerful tool for direct molecular visualization at the single-cell level.
关键词： NSOM,nanoscale imaging,AFM,cell surface molecules,QD
更新于2025-09-10 09:29:36
-
Optical vortex phase determination for nanoscale imaging
摘要： In this research we develop a principle of optical vortex phase analysis and its application to surface imaging with high accuracy measurements in nanoscale range. Two-coordinate scanning of the sample allow to retrieve an information about shape and roughness for optically transparent and reflecting surfaces exceeding optical diffraction limit. The interference between singular beam and reference wave, in general, carrying optical vortex with single or doubled topological charge allow to extract the data about phase delay caused by surface features or refraction. This method is also applicable for non-destructive testing of biological structures and live cells in real-time regime. Automatic processing of vortex interferograms allow to achieve a vertical and longitudinal resolution down to 1,75 nm and 7 nm respectively for visible light sources.
关键词： biological structures,nanoscale imaging,surface roughness,non-destructive testing,optical vortex phase analysis
更新于2025-09-09 09:28:46
-
Imaging the Optical Fields of Functionalized Silver Nanowires through Molecular TERS
摘要： We image 4-mercaptobenzonitrile-functionalized silver nanowires (~20 nm diameter) through tip-enhanced Raman scattering (TERS). The enhanced local optical field-molecular interactions that govern the recorded hyperspectral TERS images are dissected through hybrid finite-difference time-domain-density functional theory simulations. Our forward simulations illustrate that the recorded spatio-spectral profiles of the chemically functionalized nanowires may be reproduced by accounting for the interaction between orientationally averaged molecular polarizability derivative tensors and enhanced incident/scattered local fields polarized along the tip axis. In effect, we directly map the enhanced optical fields of the nanowire in real space through TERS. The simultaneously recorded atomic force microscopy (AFM) images allow a direct comparison between our attainable spatial resolution in topographic (13 nm) and TERS (5 nm) imaging measurements performed under ambient conditions. Overall, our described protocol enables local electric-field imaging with few nm precision through molecular TERS, and it is therefore generally applicable to a variety of plasmonic nano-structures.
关键词： silver nanowires,TERS,nanoscale imaging,optical fields,tip-enhanced Raman scattering
更新于2025-09-09 09:28:46