Featured Research

from universities, journals, and other organizations

Nanoclusters Of 2-8 Silver Atoms May Be Basis For New Optical Storage Technique

Date:
January 31, 2001
Source:
Georgia Institute Of Technology
Summary:
Nanoclusters composed of 2-8 silver atoms could be the basis for a new type of optical data storage. Fluorescent emissions from the clusters could potentially also be used in biological labels and electroluminescent displays.

Nanoclusters composed of 2-8 silver atoms could be the basis for a new type of optical data storage. Fluorescent emissions from the clusters could potentially also be used in biological labels and electroluminescent displays.

Related Articles


Writing in the journal Science, researchers at the Georgia Institute of Technology report that they have successfully demonstrated binary optical storage with the new system, writing and reading simple images recorded on thin films made up of silver oxide (Ag2O) nanoparticles.

"These nanomaterials have a remarkable new property: when you shine blue light with a wavelength of less than 520 nanometers onto them, you switch on their ability to fluoresce," said Robert M. Dickson, assistant professor of chemistry and biochemistry at Georgia Tech. "You can then read the fluorescence nondestructively by illuminating the clusters with longer-wavelength light."

The researchers begin by producing extremely thin films (less than 20 nanometers thick) of silver oxide nanoparticles on a glass slide. They then selectively expose portions of the film to light in the blue spectrum. The light chemically reduces particles near the surface of the film, partially converting them to clusters of silver atoms. When researchers then expose these photoactivated silver clusters to longer wavelength (greater than 520 nanometers) green light, they fluoresce strongly, emitting red light easily visible to the naked eye. Silver oxide particles not photoactivated by exposure to the blue light do not fluoresce.

Dickson's research group, including Lynn A. Peyser, Amy E. Vinson and Andrew P. Bartko, have used the technique to store images of simple geometric shapes and the letter "L."

When studied under a microscope, the individual silver particles display an additional property that may ultimately prove useful for increasing the density of optical data storage.

"If you look at an individual particle through the microscope, you see green emission, then red emission, then yellow emission all from the same particle," Dickson said. "Not only are you generating fluorescence, but you presumably are also changing the size and/or geometry of the cluster, which causes it to emit different wavelengths."

By using the correct distribution of particle sizes, these multi-color emissions could allow storage of more than one bit of information in each data point. And if the particles could be distributed in a three-dimensional matrix, they could provide a very dense storage medium that could be written and read in parallel.

"We have already demonstrated binary optical storage because we can write fluorescent patterns in which an individual particle is either on or off," Dickson noted. "But we can imagine being able to write and read more than binary storage. These silver clusters could potentially be very useful optical storage materials because of the potential for writing and reading in parallel, and/or storing more than one bit of information per data point."

When exposed to laser-generated blue light at a wavelength of 515 nanometers, the nanoclusters produce a seemingly random blinking pattern of yellow, red and green light. Exposure to blue light, however, photoactivates additional silver oxide particles, destroying the original image.

Images stored on the silver oxide film can be read nondestructively by green light for at least two days, the longest period of time the researchers left them on the stage of their microscope. How long the effect will persist is a topic for further study.

Though they have demonstrated an ability to optically write and read information with the new system, the researchers do not yet know if the information can be optically erased and the film re-written.

Fluorescence has previously been reported in silver clusters at low temperatures and in rare gas environments, but Dickson believes this is the first time the phenomenon has been reported at room temperature.

Having demonstrated a potentially valuable new technique, the researchers are now working to understand the fundamental issues governing the properties of the nanoclusters.

"We really want to understand the underlying physics and chemistry of this material," Dickson said. "While we have an eye toward developing applications, the issue now is understanding what gives rise to the fluorescence, understanding the size and geometry of these clusters, how to control the composition and what factors are important for generating the fluorescence."

A physical chemist with a background in optically-active organic dyes, Dickson expected to see fluorescence in the silver clusters, but he was surprised at the strength of the emissions produced. "We were also amazed at the beauty of the fluorescence from the sample," he added.

Photoactivation of silver halide crystals has been the basis for commercial photographic processes used for more than 100 years. The new technique is similar, though photographic materials use larger crystals of silver salts as the photoactivable material.

While the researchers do not yet understand why the particles fluoresce, Dickson believes the phenomenon's cause relates to the quantum mechanical properties of atomic silver. "Interesting things happen when materials that behave in one way as bulk materials are reduced to the small scale," he added.

Students involved in this research were supported in part by the Georgia Tech Molecular Design Institute and the National Science Foundation's Research Experiences for Undergraduates program. Provisional patent protection has been applied for to protect the technique.

The paper appeared in the January 5 issue of Science.


Story Source:

The above story is based on materials provided by Georgia Institute Of Technology. Note: Materials may be edited for content and length.


Cite This Page:

Georgia Institute Of Technology. "Nanoclusters Of 2-8 Silver Atoms May Be Basis For New Optical Storage Technique." ScienceDaily. ScienceDaily, 31 January 2001. <www.sciencedaily.com/releases/2001/01/010131074615.htm>.
Georgia Institute Of Technology. (2001, January 31). Nanoclusters Of 2-8 Silver Atoms May Be Basis For New Optical Storage Technique. ScienceDaily. Retrieved November 23, 2014 from www.sciencedaily.com/releases/2001/01/010131074615.htm
Georgia Institute Of Technology. "Nanoclusters Of 2-8 Silver Atoms May Be Basis For New Optical Storage Technique." ScienceDaily. www.sciencedaily.com/releases/2001/01/010131074615.htm (accessed November 23, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Sunday, November 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

Toyota's Hydrogen Fuel-Cell Green Car Soon Available in the US

AFP (Nov. 21, 2014) Toyota presented its hydrogen fuel-cell compact car called "Mirai" to US consumers at the Los Angeles auto show. The car should go on sale in 2015 for around $60.000. It combines stored hydrogen with oxygen to generate its own power. Duration: 01:18 Video provided by AFP
Powered by NewsLook.com
Google Announces Improvements To Balloon-Borne Wi-Fi Project

Google Announces Improvements To Balloon-Borne Wi-Fi Project

Newsy (Nov. 21, 2014) In a blog post, Google said its balloons have traveled 3 million kilometers since the start of Project Loon. Video provided by Newsy
Powered by NewsLook.com
Raw: Paralyzed Marine Walks With Robotic Braces

Raw: Paralyzed Marine Walks With Robotic Braces

AP (Nov. 21, 2014) Marine Corps officials say a special operations officer left paralyzed by a sniper's bullet in Afghanistan walked using robotic leg braces in a ceremony to award him a Bronze Star. (Nov. 21) Video provided by AP
Powered by NewsLook.com
British 'Bio-Bus' Is Powered By Human Waste

British 'Bio-Bus' Is Powered By Human Waste

Buzz60 (Nov. 21, 2014) British company GENeco debuted what its calling the Bio-Bus, a bus fueled entirely by biomethane gas produced from food scraps and sewage. Jen Markham explains. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins