Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Growth Spurts: Berkeley Lab Researchers Record First Real-Time Direct Observations of Nanocrystal Growth in Solution

Haimei Zheng is a chemist in the research group of Paul Alivisatos who was the lead author on a Science paper that reports the first ever direct observations in real-time of the growth of single nanocrystals in solution. (Photo by Majed Abolfazli)
Haimei Zheng is a chemist in the research group of Paul Alivisatos who was the lead author on a Science paper that reports the first ever direct observations in real-time of the growth of single nanocrystals in solution. (Photo by Majed Abolfazli)

Abstract:
The veil is being lifted from the once unseen world of molecular activity. Not so long ago only the final products were visible and scientists were forced to gauge the processes behind those products by ensemble averages of many molecules.

Growth Spurts: Berkeley Lab Researchers Record First Real-Time Direct Observations of Nanocrystal Growth in Solution

Berkeley, CA | Posted on August 11th, 2009

The limitations of that approach have become clear with the advent of technologies that allow for the observation and manipulation of single molecules. A prime example is the recent first ever direct observations in real-time of the growth of single nanocrystals in solution, which revealed that much of what we thought we knew is wrong.

Interim Berkeley Lab Director Paul Alivisatos and Ulrich Dahmen, director of Berkeley Lab's National Center for Electron Microscopy (NCEM), led a team of experts in nanocrystal growth and electron microscopy who combined their skills to observe the dynamic growth of colloidal platinum nanocrystals in solution with subnanometer resolution. Their results showed that while some crystals in solution grow steadily in size via classical nucleation and aggregation - meaning molecules collide and join together - others grow in fits and spurts, driven by "coalescence events," in which small crystals randomly collide and fuse together into larger crystals. Despite their distinctly different growth trajectories, these two processes ultimately yield a nearly monodisperse distribution of nanocrystals, meaning the crystals are all approximately the same size and shape.

"Coalescence events have been previously observed in flask synthesis of colloidal nanocrystals and has been considered detrimental for achieving monodisperse colloidal nanocrystals," says Haimei Zheng, a chemist in Alivisatos' research group, who was the lead author on a paper that reported these results in the journal Science. "In our study, we found that coalescence events are frequently involved in the early stage of nanocrystal growth and yet monodisperse nanocrystals are still formed."

Says Alivisatos, a chemist who holds joint appointments with Berkeley Lab and the University of California at Berkeley where he is the Larry and Diane Bock professor of Nanotechnology, "This direct observation of nanocrystal growth trajectories revealed a set of pathways more complex than those previously envisioned and enables us to re-think the nanocrystal growth mechanism with an eye towards more controlled synthesis."

The Science paper was titled: "Observation of Single Colloidal Platinum Nanocrystal Growth Trajectories." Co-authoring this paper with Zheng, Alivisatos and Dahmen were Rachel Smith, Young-wook Jun and Christian Kisielowski.

Nanocrystals are projected to play important roles in a wide-ranging number of technologies including solar and fuel cell, catalysis, electronics and photonics, medicine, and imaging and sensing. The key to success will be the ability to synthesis nanocrystals with desired physical properties. This will require a much better understanding of colloidal nanocrystal growth mechanisms. While the past two decades have seen tremendous advances in the synthesis of semiconductor, metal and dielectric nanocrystals, these advances have generally been realized through trial and error chemistry. A much more directed and controlled approach to nanocrystal synthesis is needed.

A new technique known as "liquid cell in situ transmission electron microscopy," in which the powerful resolution capabilities of a transmission electron microscope (TEM) are brought to bear on a liquid cell that allows liquids to be observed inside a vacuum, enables the visualization of single nanoparticles in solution. The Berkeley researchers deployed this technique on NCEM's JEOL 3010 In-Situ microscope. Utilizing an electron beam operating at 300 kilovolts of energy, the JEOL 3010 provides outstanding specimen penetration and spatial resolution of about 8 angstroms through the thick liquid cell sample.

"The JEOL 3010 In-Situ Microscope is our best machine for imaging dynamic events, and at 300kV the electron beam has enough penetrating power to maintain high resolution, even when looking through a liquid confined between two thin solid windows," says NCEM director Dahmen. "Our resolution is significantly higher than any previous studies of this nature, which made it possible for us to measure the movement and growth of individual colloidal particles only a few nanometers in size."

Zheng, Dahmen, Alivisatos and their colleagues used the JEOL 3010 and liquid cells microfabricated from a pair of 100-micron-thick silicon wafers with 20 nanometer thick silicon nitride membrane windows to image the growth trajectories of platinum nanocrystals in solution. Platinum nanocrystals are an ideal system for such studies because their high electron contrast allows liquid-cell TEM imaging of individual particles. The JEOL 3010's electron beam was used to both trigger nucleation and drive crystal growth through reduction of the platinum cations.

"Video-rate acquisition allowed us to track nanocrystal growth trajectories from frame-to-frame," says Zheng. "This allowed us to observe that each nanocrystal can either grow steadily through the addition of monomers from solution or by merging with another nanocrystal in random coalescence events."

Zheng says it has been assumed that coalescence events would result in some crystals being much larger than others, a bad thing in that the physical properties of nanocrystals are so dependent upon size and shape that for many applications it is critical that monodispersed nanocrystals be produced during synthesis. Consequently, strategies such as the use of surfactants to coat nanocrystal surfaces have been adopted to avoid coalescence events.

"Our observations provide invaluable direct information on how nanocrystals grow and indicate how we might directly control nanocrystal synthesis for tailored properties," says Zheng. "Also, our in situ liquid cell TEM technique can be applied to other areas of research such as soft matter imaging and nanoparticle catalysis, and offers great potential for addressing many fundamental issues in materials science, chemistry and other fields of science."

Says Dahmen, "From a microscopist's point of view, the ability to observe nanoparticles in liquid solution opens new opportunities in an area that has traditionally been off-limits because electron microscopes require vacuum conditions. We can now see directly what before could only be surmised from the statistical behavior of the ensemble. It's like understanding traffic by watching individual cars instead of listening to the traffic report."

####

About Berkeley Lab
Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research for DOE’s Office of Science and is managed by the University of California. Visit our Website at www.lbl.gov/

NCEM is a U.S. Department of Energy national user facility that is hosted at Berkeley Lab. Established in 1983, it stands today as one of the world’s foremost centers for electron microscopy and microcharacterization.

For more information, please click here

Contacts:
Lynn Yarris
(510) 486-5375

Copyright © Berkeley Lab

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.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Ultrathin device harvests electricity from human motion July 23rd, 2017

The July 23 close fly-by of asteroid 2017 BS5 is explored in a Q&A with Dr. John S. Lewis, chief scientist at Deep Space Industries July 23rd, 2017

Scientists announce the quest for high-index materials: All-dielectric nanophotonics: The quest for better materials and fabrication techniques July 22nd, 2017

Pulses of electrons manipulate nanomagnets and store information: Scientists use electron pulses to create and manipulate nanoscale magnetic excitations that can store data July 21st, 2017

Nanomedicine

Scientists announce the quest for high-index materials: All-dielectric nanophotonics: The quest for better materials and fabrication techniques July 22nd, 2017

Probiotics: Novel biosynthetic tool to develop metallic nanoparticles: This research article by Dr. Nida Akhtar et al has been published in Recent Patents on Drug Delivery & Formulation, Volume 11, Issue 1, 2017 July 20th, 2017

Semiliquid chains pulled out of a sea of microparticles July 20th, 2017

'Upconverted' light has a bright future: Rice University professor developing plasmon-powered devices for medicine, security, solar cells July 17th, 2017

Sensors

Giant enhancement of electromagnetic waves revealed within small dielectric particles: Scientists have done for the first time direct measurements of giant electromagnetic fields July 8th, 2017

Bosch announces high-performance MEMS acceleration sensors for wearables June 27th, 2017

Leti’s Autonomous-Vehicle System Embedded in Infineon’s AURIX Platform: Leti’s Low-Power, Multi-Sensor System that Transforms Distance Data into Clear Information About the Driving Environment Will Be Demonstrated at ITS Meeting in Strasbourg, June 19-22 June 20th, 2017

New diode features optically controlled capacitance: Israeli researchers have developed a new optically tunable capacitor with embedded metal nanoparticles, creating a metal-insulator-semiconductor diode that is tunable by illumination. June 8th, 2017

Nanoelectronics

Tokyo Institute of Technology research: Antiaromatic molecule displays record electrical conductance July 19th, 2017

A firefly's flash inspires new nanolaser light July 18th, 2017

GLOBALFOUNDRIES and VeriSilicon To Enable Single-Chip Solution for Next-Gen IoT Networks: Integrated solution leverages GF’s 22FDX® technology to decrease power, area, and cost for NB-IoT and LTE-M applications July 14th, 2017

Thinking thin brings new layering and thermal abilities to the semiconductor industry: In a breakthrough for the semiconductor industry, researchers demonstrate a new layer transfer technique called "controlled spalling" that creates many thin layers from a single gallium nitride July 11th, 2017

Announcements

Ultrathin device harvests electricity from human motion July 23rd, 2017

The July 23 close fly-by of asteroid 2017 BS5 is explored in a Q&A with Dr. John S. Lewis, chief scientist at Deep Space Industries July 23rd, 2017

Scientists announce the quest for high-index materials: All-dielectric nanophotonics: The quest for better materials and fabrication techniques July 22nd, 2017

Pulses of electrons manipulate nanomagnets and store information: Scientists use electron pulses to create and manipulate nanoscale magnetic excitations that can store data July 21st, 2017

Tools

Scientists announce the quest for high-index materials: All-dielectric nanophotonics: The quest for better materials and fabrication techniques July 22nd, 2017

Coupling a nano-trumpet with a quantum dot enables precise position determination July 14th, 2017

Nanometrics to Announce Second Quarter Financial Results on August 1, 2017 July 14th, 2017

Nanometrics Introduces SpectraProbe Analysis Software: Advanced software and algorithms enhancing Nanometrics metrology fleet capabilities fab-wide July 13th, 2017

Energy

'Upconverted' light has a bright future: Rice University professor developing plasmon-powered devices for medicine, security, solar cells July 17th, 2017

Making two out of one: FAU researchers have explained the mechanism behind a process that can increase the efficiency of organic solar cells July 12th, 2017

Argonne National Laboratory’s Continuous ALD Technology Licensed Exclusively to Forge Nano July 7th, 2017

Tiny bubbles provide tremendous propulsion in new microparticles research-Ben-Gurion U. June 21st, 2017

Fuel Cells

Argonne National Laboratory’s Continuous ALD Technology Licensed Exclusively to Forge Nano July 7th, 2017

Electrocatalyst nanostructures key to improved fuel cells, electrolyzers June 5th, 2017

Stanford scientists use nanotechnology to boost the performance of key industrial catalyst May 18th, 2017

MIT Energy Initiative awards 10 seed fund grants for early-stage energy research May 4th, 2017

Nanobiotechnology

Probiotics: Novel biosynthetic tool to develop metallic nanoparticles: This research article by Dr. Nida Akhtar et al has been published in Recent Patents on Drug Delivery & Formulation, Volume 11, Issue 1, 2017 July 20th, 2017

Semiliquid chains pulled out of a sea of microparticles July 20th, 2017

Researchers revolutionize vital conservation tool with use of gold nanotechnology and lasers: Cryopreservation study results have sweeping implications for wildlife conservation and human health July 15th, 2017

Nanomedicine opens door to precision medicine for brain tumors July 12th, 2017

Photonics/Optics/Lasers

Scientists announce the quest for high-index materials: All-dielectric nanophotonics: The quest for better materials and fabrication techniques July 22nd, 2017

Nanoparticles could spur better LEDs, invisibility cloaks July 19th, 2017

'Upconverted' light has a bright future: Rice University professor developing plasmon-powered devices for medicine, security, solar cells July 17th, 2017

Researchers revolutionize vital conservation tool with use of gold nanotechnology and lasers: Cryopreservation study results have sweeping implications for wildlife conservation and human health July 15th, 2017

Solar/Photovoltaic

'Upconverted' light has a bright future: Rice University professor developing plasmon-powered devices for medicine, security, solar cells July 17th, 2017

Making two out of one: FAU researchers have explained the mechanism behind a process that can increase the efficiency of organic solar cells July 12th, 2017

Thinking thin brings new layering and thermal abilities to the semiconductor industry: In a breakthrough for the semiconductor industry, researchers demonstrate a new layer transfer technique called "controlled spalling" that creates many thin layers from a single gallium nitride July 11th, 2017

Tiny bubbles provide tremendous propulsion in new microparticles research-Ben-Gurion U. June 21st, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project