Category Physics

Optically-driven mechanical oscillator fabricated using a plasmomechanical metamaterial.

A device fabricated using a plasmomechanical metamaterial, operates through a unique mechanism that couples its optical and mechanical resonances, enabling it to oscillate indefinitely using energy absorbed from light. This work demonstrates a metamaterial-based approach to develop an optically-driven mechanical oscillator. The device can potentially be used as a new frequency reference to accurately keep time in GPS, computers, wristwatches and other devices. Other potential applications include high precision sensors and quantum transducers.

Researchers engineered the metamaterial-based device by integrating tiny light absorbing nanoantennas onto nanomechanical oscillators...

The schematic depicts the time-resolved photoemission electron microscopy instrumentation that allowed the Femtosecond Spectroscopy Unit to visualize electron movements. The 800nm pump pulse (red) excites electrons while the weaker 266nm probing pulse (blue) allows for different measurements of electron movements to be taken. Credit: Michael Man

Ever since J.J. Thompson’s 1897 discovery of the electron, scientists have attempted to describe the subatomic particle’s motion using a variety of different means. New research from the Femtosecond Spectroscopy Unit at the Okinawa Institute of Science and Technology Graduate University (OIST) has made this process much easier.

I wanted to see the electrons move, not just to explain their motion by measuring a change of light transmission and refle...

Schematic of a transistor with a molybdenum disulfide channel and 1-nanometer carbon nanotube gate. Credit: Sujay Desai/UC Berkeley

Research breaks major barrier in transistor size by creating gate only 1nm long. For more than a decade, engineers have been eyeing the finish line in the race to shrink the size of components in integrated circuits. They knew that the laws of physics had set a 5nm threshold on the size of transistor gates among conventional semiconductors, about 1/4 the size of high-end 20nm-gate transistors now on the market.

“We made the smallest transistor reported to date,” said Javey, lead principal investigator of the Electronic Materials program in Berkeley Lab’s Materials Science Division. “The gate length is considered a defining dimension of the transistor...

This image shows a new efficient and low-cost method for hydrogenation of graphene with visible light. Credit: Joakim Bergman, AstraZeneca

“The reaction is convenient and cheap, and hydrogenated graphene may be applied within areas such as hydrogen storage. Additionally, upon functionalization of graphene one can open a bandgap and this fact is of high relevance for electronics applications,” says Prof. Henrik Ottosson.

Graphene reacts with formic acid in a water solution upon irradiation with visible light. In the reaction, formic acid acts as masked hydrogen and a material is produced where hydrogen extensively has been added to graphene. One says that graphene has been hydrogenated. Yet, graphene research is a side-project in Henrik Ottosson’s group...