Nanoscale Cathodoluminescence Thermometry with a Lanthanide-Doped Heavy-Metal Oxide in Transmission Electron Microscopy.

When navigated by the available energy of a system, often provided in the form of heat, physical processes or chemical reactions fleet on a free-energy landscape, thus changing the structure. In transmission electron microscopy (TEM), where material structures are measured and manipulated inside the microscope while being subjected to external stimuli such as electrical fields, laser irradiation, or mechanical stress, it is necessary to precisely determine the local temperature of the specimen to provide a comprehensive understanding of material behavior and to establish the relationship among energy, structure, and properties at the nanoscale. Here, we propose using cathodoluminescence (CL) spectroscopy in TEM for measurement of the local temperature.

Upconversion Material-Plasmonic Metal-Semiconductor Ternary Heteronanostructures for Wide-Range Solar-to-Chemical Energy Conversion.

Harvesting full-spectrum solar energy is a critical issue for developing high-performance photocatalysts. Here, we report a hierarchical heteronanostructure consisting of upconverting, plasmonic, and semiconducting materials as a solar-to-chemical energy conversion platform that can exploit a wide range of sunlight (from ultraviolet (UV) to near-infrared). Lanthanide-doped NaYF nanorod-spherical Au nanocrystals-TiO ternary hybrid nanostructures with a well-controlled configuration and intimate contact between the constituent materials could be synthesized by a wet-chemical method.

Femtosecond-resolved imaging of a single-particle phase transition in energy-filtered ultrafast electron microscopy.

Using an energy filter in transmission electron microscopy has enabled elemental mapping at the atomic scale and improved the precision of structural determination by gating inelastic and elastic imaging electrons, respectively. Here, we use an energy filter in ultrafast electron microscopy to enhance the temporal resolution toward the domain of atomic motion. Visualizing transient structures with femtosecond temporal precision was achieved by selecting imaging electrons in a narrow energy distribution from dense chirped photoelectron packets with broad longitudinal momentum distributions and thus typically exhibiting picosecond durations.

Synthesis of Thermally Stable and Highly Luminescent Cs Cu Cl I Nanocrystals with Nonlinear Optical Response.

Low-dimensional Cu(I)-based metal halide materials are gaining attention due to their low toxicity, high stability and unique luminescence mechanism, which is mediated by self-trapped excitons (STEs). Among them, Cs Cu Cl I , which emits blue light, is a promising candidate for applications as a next-generation blue-emitting material. In this article, an optimized colloidal process to synthesize uniform Cs Cu Cl I nanocrystals (NCs) with a superior quantum yield (QY) is proposed.

Ultrafast Excited-State Proton Transfer of a Cationic Superphotoacid in a Nanoscopic Water Pool.

The excited-state proton transfer (ESPT) of a cationic superphotoacid, -methyl-7-hydroxyquinolium, was studied within the water pool of an anionic aerosol-OT (AOT), bis(2-ethylhexyl) sulfosuccinate, reverse micelle (RM). Previously, we had found that the cationic photoacid residing at the anionic AOT interface was conducive to ESPT to the bound water having concentric heterogeneity on the time scale of hundreds of picoseconds to nanoseconds. In our present study, on the time scale of hundreds of femtoseconds to a few tens of picoseconds, the photoacid underwent an ultrafast ESPT influenced by mobile water constituting the core of the RM.

Intrachain photophysics of a donor-acceptor copolymer.

By taking advantage of bulk-heterojunction structures formed by blending conjugated donor polymers and non-fullerene acceptors, organic photovoltaic devices have recently attained promising power conversion efficiencies of above 18%. For optimizing organic photovoltaic devices, it is essential to understand the elementary processes that constitute light harvesters. Utilising femtosecond-resolved spectroscopic techniques that can access the timescales of locally excited (LE) state and charge-transfer (CT)/-separated (CS) states, herein we explored their photophysics in single chains of the top-notch performance donor-acceptor polymer, PM6, which has been widely used as a donor in state-of-the-art non-fullerene organic photovoltaic devices, in a single LE state per chain regime.