Small Methods

Novel crystal patterning method shows promise for photomechanical applications

This study reports the first attempt to characterize the quality, defects, and strain of as-grown monolayer transition metal dichalcogenide (IMDC)-based 2D materials through exciton anisotropy. A standard ellipsometric parameter (Ψ) to observe anisotropic exciton behavior in monolayer 2D materials is used. According to the strong exciton effect from phonon-electron coupling processes, the change in the exciton in the Van Hove singularity is sensitive to lattice distortions such as defects and strain. In comparison with Raman spectroscopy, the variations in exciton anisotropy in Ψ are more sensitive for detecting slight changes in the quality and strain of monolayer MDC films. Moreover, the optical power requirement for TMDC characterization through exciton anisotropy in Ψ is ~10-5 mW·cm-2, which is significantly less than that of Raman spectroscopy (~106 mW·cm-2). The standard deviation of the signals varies with strain (defects) in Raman spectra and exciton anisotropies in Ψ are 0.700 (0.795) and 0.033 (0.073), indicating that exciton anisotropy is more sensitive to slight changes in the quality of monolayer TMDC films.

Researchers at Nano Life Science Institute (WPI-NanoLSI), Kanazawa University report in Small Methods the 3D imaging of a suspended nanostructure. The technique used is an extension of atomic force microscopy and is a promising approach for visualizing various 3D biological systems.

Researchers from Osaka University and collaborating partners enhanced DNA detection in silicon nitride nanopores by means of a water–glycerol viscosity gradient. Use of common chemistry under electrochemical flow enabled straightforward detection of individual DNA molecules. With further development, the results of this work could dramatically speed up and lower the cost of genomic sequencing, and facilitate unprecedented integration with compact electronics.