Home > Press > Researchers discern the shapes of high-order Brownian motions
This image spatially maps and visualizes the shapes of multimode Brownian motions. The to of the image is a false-colored scanning electron micrographs of a silicon carbide (SiC) microdisk supported by a central pedestal made of 500nm-thick silicon oxide. The bottom image is a scanned map of vibrations of the microdisk due to a high-order mode Brownian motion.
Credit: Philip Feng |
Abstract:
For the first time, scientists have vividly mapped the shapes and textures of high-order modes of Brownian motions--in this case, the collective macroscopic movement of molecules in microdisk resonators--researchers at Case Western Reserve University report.
To do this, they used a record-setting scanning optical interferometry technique, described in a study published today in the journal Nature Communications.
The new technology holds promise for multimodal sensing and signal processing, and to develop optical coding for computing and other information-processing functions by exploiting the spatially resolved multimode Brownian resonances and their splitting pairs of modes.
"What we found agrees with the expected Brownian motions in high-order modes," said Philip Feng, assistant professor of electrical engineering and computer science at Case Western Reserve and senior author of the study. "But it has been pretty amazing and exhilarating to directly visualize these modes down to the fundamental limit of intrinsic Brownian motions."
In his lab at Case School of Engineering, Feng worked closely with research associate Max Zenghui Wang and PhD student Jaesung Lee on the study.
Interferometry uses the interference of light waves reflected off a surface to measure distances, a technique invented by Case School of Applied Science physicist Albert A. Michelson (who won the Nobel prize in science in 1907). Michelson and Western Reserve University chemist Edward Morley used the instrument to famously disprove that light traveled through "luminous ether" in 1887, setting the groundwork for Albert Einstein's theory of relativity.
The technology has evolved since then. The keys to Feng's new interferometry technique are focusing a tighter-than-standard laser spot on the surface of novel silicon carbide microdisks.
The microdisks, which sit atop pedestals of silicon oxide like cymbals on stands, are extremely sensitive to the smallest fluctuations arising from Brownian motions, even at thermodynamic equilibrium. Hence, they exhibit very small oscillations without external driving forces. These oscillations include fundamental and higher modes, called thermomechanical resonances.
Some of the light from the laser reflects back to a sensor after striking the top surface of the silicon dioxide film. And some of the light is refracted through the film and reflected back on a different path, causing interference in the light waves.
The narrow laser spot scans the disk surface and measures movement, or displacement, of the disk with a sensitivity of about 7 femtometers per square-root of a hertz at room temperature, which researchers believe is a record for interferometric systems. To put that in perspective, the width of a hair is about 40 microns, and a femtometer is 100 million times smaller than a micron.
Although higher frequency modes have small motion amplitudes, the technology enabled the group to spatially map and clearly visualize the first through ninth Brownian modes in the high frequency band, ranging from 5.78 to 26.41 megahertz.
In addition to detecting the shapes and textures of Brownian motions, multimode mapping identified subtle structural imperfections and defects, which are ubiquitous but otherwise invisible, or can't be quantified most of the time. This capability may be useful for probing the dynamics and propagation of defects and defect arrays in nanodevices, as well as for future engineering of controllable defects to manipulate information in silicon carbide nanostructures.
The high sensitivity and spatial resolution also enabled them to identify mode splitting, crossing and degeneracy, spatial asymmetry and other effects that may be used to encode information with increasing complexity. The researchers are continuing to explore the capabilities of the technology.
####
For more information, please click here
Contacts:
Kevin Mayhood
216-534-7183
Copyright © Case Western Reserve University
If you have a comment, please Contact us.Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.
Related News Press |
News and information
Researchers develop artificial building blocks of life March 8th, 2024
Physics
Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024
Optically trapped quantum droplets of light can bind together to form macroscopic complexes March 8th, 2024
Scientists use heat to create transformations between skyrmions and antiskyrmions January 12th, 2024
Focused ion beam technology: A single tool for a wide range of applications January 12th, 2024
Imaging
Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024
Possible Futures
Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024
Molecular Nanotechnology
Scientists push the boundaries of manipulating light at the submicroscopic level March 3rd, 2023
First electric nanomotor made from DNA material: Synthetic rotary motors at the nanoscale perform mechanical work July 22nd, 2022
Nanotech scientists create world's smallest origami bird March 17th, 2021
Discoveries
What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024
Researchers’ approach may protect quantum computers from attacks March 8th, 2024
High-tech 'paint' could spare patients repeated surgeries March 8th, 2024
Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024
Announcements
What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024
Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024
Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers/Posters
Researchers develop artificial building blocks of life March 8th, 2024
Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024
Tools
Ferroelectrically modulate the Fermi level of graphene oxide to enhance SERS response November 3rd, 2023
The USTC realizes In situ electron paramagnetic resonance spectroscopy using single nanodiamond sensors November 3rd, 2023
The latest news from around the world, FREE | ||
Premium Products | ||
Only the news you want to read!
Learn More |
||
Full-service, expert consulting
Learn More |
||