In the research of advanced materials based on nanoscience and nanotechnology, it is often desirable to measure nanoscale local electrical conductivity at a designated position of a given sample. For this purpose, multiple-probe scanning probe microscopes (MP-SPMs), in which two, three or four scanning tunneling microscope (STM) or atomic force microscope (AFM) probes are operated independently, have been developed. Each probe in an MP-SPM is used not only for observing high-resolution STM or AFM images but also for forming an electrical contact enabling nanoscale local electrical conductivity measurement. The world's first double-probe STM (DP-STM) developed by the authors, which was subsequently modified to a triple-probe STM (TP-STM), has been used to measure the conductivities of one-dimensional metal nanowires and carbon nanotubes and also two-dimensional molecular films. A quadruple-probe STM (QP-STM) has also been developed and used to measure the conductivity of two-dimensional molecular films without the ambiguity of contact resistance between the probe and sample. Moreover, a quadruple-probe AFM (QP-AFM) with four conductive tuning-fork-type self-detection force sensing probes has been developed to measure the conductivity of a nanostructure on an insulating substrate. A general-purpose computer software to control four probes at the same time has also been developed and used in the operation of the QP-AFM. These developments and applications of MP-SPMs are reviewed in this paper.
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http://dx.doi.org/10.1002/adma.201200257 | DOI Listing |
Scattering-type scanning near-field optical microscopy (s-SNOM) enables sub-diffraction spectroscopy, featuring high sensitivity to small spatial permittivity variations of the sample surface. However, due to the complexity of the near-field probe-sample interaction, the quantitative extraction of the complex permittivity leads to a computationally demanding inverse problem, requiring further approximation of the system to an invertible model. Black-box calibration methods, similar to those applied to microwave vector network analyzers, allow the extraction of the permittivity without detailed electromagnetic modeling of the probe-sample interaction.
View Article and Find Full Text PDFPhotoacoustics
June 2023
Hokkaido University, Sapporo 060-0808, Japan.
We present a picosecond optoacoustic technique for mapping both the longitudinal sound velocity and the refractive index in solids by automated measurement at multiple probe incidence angles in time-domain Brillouin scattering. Using a fused silica sample with a deposited titanium film as an optoacoustic transducer, we map and in the depth direction. Applications include the imaging of sound velocity and refractive index distributions in three dimensions in inhomogeneous samples such as biological cells.
View Article and Find Full Text PDFMicrosc Microanal
February 2021
National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA94720, USA.
One of the primary uses for transmission electron microscopy (TEM) is to measure diffraction pattern images in order to determine a crystal structure and orientation. In nanobeam electron diffraction (NBED), we scan a moderately converged electron probe over the sample to acquire thousands or even millions of sequential diffraction images, a technique that is especially appropriate for polycrystalline samples. However, due to the large Ewald sphere of TEM, excitation of Bragg peaks can be extremely sensitive to sample tilt, varying strongly for even a few degrees of sample tilt for crystalline samples.
View Article and Find Full Text PDFAnal Chem
November 2018
Key Laboratory for Advanced Materials, School of Chemistry and Molecular Engineering , East China University of Science & Technology, 200237 Shanghai , P.R. China.
Recently, a variety of strategies have been developed for single-cell detection. However, the precise probing of the given area at single-cell level is still a challenge. Here, we put forward a rapid and targeted imaging approach for the mapping of subcelluar domains, which realizes the precise injection of multifluorescence into a single living cell via an ultrasmall quartz capillary nanopipette (∼100 nm) and can successfully transport different fluorescent probe molecules to the pointing subcellullar area around the tip in the cytoplasm within 20 s.
View Article and Find Full Text PDFDespite the long-standing importance of transient absorption (TA) spectroscopy, many researchers remain frustrated by the difficulty of measuring the nanosecond range in a wide spectral range. To address this shortcoming, we propose a TA spectrophotometer in which there is no synchronization between a pump pulse and a train of multiple probe pulses from a picosecond supercontinuum light source, termed the randomly-interleaved-pulse-train (RIPT) method. For each pump pulse, many monochromatized probe pulses impinge upon the sample, and the associated pump-probe time delays are determined passively shot by shot with subnanosecond accuracy.
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