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September
14, 2004
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Scientists
Tame 'Hip Hop' Atoms
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A
40-nanometer-wide NIST logo made with cobalt atoms
on a copper surface. The ripples in the background
are made by electrons, which create a fluid-like
layer at the copper surface. Each atom on the surface
acts like a pebble dropped in a pond.
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In
an effort
to put more science into the largely trial and error building
of nanostructures, physicists at the National
Institute of Standards and Technology (NIST) have demonstrated
new methods for placing what are typically unruly individual
atoms at precise locations on a crystal surface.
Reported
in the Sept. 9, 2004, online version of the journal Science,
the advance enables scientists to observe and control, for the
first time, the movement of a single atom back and forth between
neighboring locations on a crystal and should make it easier
to efficiently build nanoscale devices "from the bottom
up," atom by atom.
Joseph
Stroscio; Robert Celotta / NIST
Click
on image for high-resolution
version.
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Colorized
version of an image created by the NIST custom-built scanning
tunneling microscope as it drags a cobalt atom across
a closely packed lattice of copper atoms. Large round
features show the cobalt atom bonding to the copper at
its preferred, lowest energy bonding site. Bright triangle-shaped
areas show the atoms bonding at a higher energy site.
The atom "screeches in protest" when the STM
tip forces it to sit at this site. Dark areas show positions
that the atom "hops" over, refusing to bond
at all.
Click
here to hear "sounds" of hip hop atoms
(You will need Real Player on your computer in order to
view. Download Real Player free of charge at the Real.Com
FreePlayer website.) |
The NIST
team was surprised to find that the atoms emitted a characteristic
electronic "noise" as they moved between two different
types
of bonding sites on the crystal surface. By converting this
electronic
signal into an audio signal, the researchers were able to "hear"
the switching take place. The sound resembles a hip hop musician’s
rhythmic "scratching" and can be used by researchers
to know in real time that atoms have moved into desired positions.
Several research groups already are using specialized
microscopes to build simple structures by moving atoms one at
a time. The NIST advance makes it easier to reliably position
atoms in very specific locations. "What we did to the atom
is something like lubricating a ball bearing so that less force
is required to move it," says Joseph Stroscio, co-author
of the Science paper.
Such basic
nanoscale construction tools will be essential for computer-controlled
assembly of more complex atomic-scale structures and devices.
These devices will operate using quantum physics principles
that only occur at the atomic scale, or may be the ultimate
miniaturization of a conventional device, such as an “atomic
switch” where the motion of a single atom can turn electrical
signals on and off.
For
more information, see www.nist.gov/public_affairs/releases/hiphopatoms.htm.
Media
Contact:
Laura
Ost, laura.ost@nist.gov,
(301) 975-4034
A
Simpler Design for X-Ray Detectors
A simplified
design for ultra-sensitive X-ray detectors offering more
precise materials analysis has been demonstrated at the
National Institute of Standards and Technology (NIST).
The advance is a step toward making
such devices cheaper and easier to produce. Users may eventually
include the semiconductor industry, which needs better
X-ray detectors
to identify and distinguish between nanoscale contaminant
particles on silicon wafers.
The
new design, described in the Sept. 13 issue of
Applied Physics Letters,* is among the latest
advances in a decade of NIST research on superconducting "transition
edge" sensors (TES). These cryogenic sensors absorb
individual X-rays and then measure the energy of the X-ray
by measuring the resulting rise in temperature. The temperature
is measured with a bilayer of normal metal and superconducting
metal that changes from zero resistance (superconducting)
to a slight resistance level in response to the heat from
the radiation. By measuring the X-ray energy, NIST researchers
can identify the X-ray "fingerprints" of
particular elements.
NIST
researchers have built systems offering 30 times better
X-ray energy resolution than detectors now used in the
semiconductor industry and are pursuing further improvements
such as novel detector geometries and materials. In contrast
to
the usual
bilayer TES design, the sensor described in the APL
paper combines the normal and superconducting metals into
one homogenous layer. Manganese impurities are added to
a 400-nanometer-thick aluminum film to lower its superconducting
transition
temperature to 100 milliKelvin. Fabrication requires
about half as many steps as the bilayer design. In addition,
the new design exhibits less "noise" in the
X-ray signals than is typical for TES sensors, as well
as a low
sensitivity to magnetic fields that could help in building
stable instruments.
Scientists
at the University of Notre Dame and Santa Clara University
also participated in the research. The work was supported
in part by NASA.
Media
Contact:
Laura
Ost, laura.ost@nist.gov,
(301) 975-4034
*S.W.
Deiker, W. Doriese, G.C. Hilton, K.D. Irwin, W.H. Rippard,
J.N. Ullom, L.R. Vale, S.T. Ruggiero, A. Williams
and B.A. Young. 2004. Superconducting transition edge sensor
using dilute AlMn alloys. Applied Physics Letters, Sept. 13.
Emergency
'Shoelacing' for Fractured Phone Systems
When
a major disaster—man-made
or natural—takes
down the phone system, who ya gonna call? No one,
'cause the phone’s dead, right? … Not if
you're using a novel emergency communications system
under
development by the Maryland start-up TeleContinuity Inc.
With initial support from the National Institute of Standards
and Technology’s Advanced Technology Program (ATP),
TeleContinuity is creating a “survivable” emergency
telephone system back-up network that keeps individuals,
companies and government agencies in touch during disasters
by seamlessly merging conventional phone lines and the
Internet.
Telecontinuity’s
system represents a shift from traditional disaster recovery
and business continuity solutions that
historically have focused on location-based backup facilities
and centralized telecom infrastructures.
The
terrorist attacks of Sept. 11, 2001, severely disrupted
phone
service at the attack sites, particularly in New York,
where the collapse of the World Trade Center damaged a major
local phone central office. Days and even weeks later, many
companies and individuals were still without phone service.
During this time, however, Internet links, utilizing different
lines and network architectures, operated continuously. TeleContinuity’s
founders realized that short-term, emergency phone service
could be activated quickly, on any scale, by cross-linking
surviving phone system links and Internet links as necessary,
a technique they called “shoelacing.”
The
company says its initial version of the software for such
an emergency
system is designed to reroute a user’s
phone service within minutes of a major telephone outage
by delivering the call to a remote phone, cellphone or even
a computer or PDA. By the end of the ATP project in the spring
of 2005, the company plans to develop an enhanced version
of
the software that allows administrators and users to monitor
and control networks in an emergency with advanced Web-based
controls. Ultimately, commercialization of the technology
will require a network of hundreds of nodes that can quickly
lace together phone and data network lines regardless of
where in the system an outage occurs.
Researchers
from the University of Maryland and the University of Pittsburgh
assisted in developing the system.
Information
on the TeleContinutity ATP project is at http://jazz.nist.gov/atpcf/prjbriefs/prjbrief.cfm?ProjectNumber=00-00-5885,
and the company’s Web site is at www.telecontinuity.com\
Media
Contact:
Michael
Baum, michael.baum@nist.gov,
(301) 975-2763
Protecting
Buildings from Airborne Threats
A
building’s ventilation and air distribution system
can play a critical role in protecting occupants from airborne
chemical, biological and radiological (CBR) agents, according
to National Institute of Standards and Technology (NIST)
researcher Andy Persily.
In an
article in the September issue of ASHRAE Journal,*
Persily, group leader in NIST’s indoor air quality
and ventilation program, urges the development of strategies
that
minimize the impact of CBR events in buildings. He says that
a building’s ventilation system can be used to actively
protect occupants by diluting CBR agents with outside air,
driving contaminants to filters or other air-cleaning equipment,
or by selectively depressurizing vulnerable parts of the building.
Lower pressures in mail rooms, loading docks and lobbies,
for instance, could inhibit CBR movement to the rest of the
building.
NIST is
currently developing building pressurization strategies that
take into account weather conditions, envelope air-tightness
and building architecture, particularly building height. Such
pressurization systems might be used with ventilation, interior
partitions and air-cleaning systems to create emergency “shelters
in place” as a refuge for occupants or a safe
escape path.
Before
considering ventilation changes to address airborne threats,
Persily stressed that building owners and managers
should understand fully the capabilities of their existing
building systems. Otherwise, some changes could make the situation
worse. He also warned against making changes to reduce CBR
vulnerability that degrade indoor air quality or comfort during
normal conditions.
Media
Contact:
John
Blair, john.blair@nist.gov,
(301) 975-4261
*A.
Persily, Building pressurization as a security tool, ASHRAE Journal,
September 2004.
Testbed
to Link Metrology Tools/Software
Continuous
inspection of product dimensions is critical in modern
manufacturing. A finished product, and all its parts, must
fit dimensional specifications. To meet this demand for
precision, manufacturers and suppliers regularly use coordinate
measuring machines along with inspection planning, execution
and analysis programs. Too often, however, these quality
control components do not communicate well, particularly
when components are mixed and matched from different vendors.
The result can be substantial costs to manufacturers who
must translate data from one system to another, retrain
workers or even buy new machines for their production lines.
The
National Institute of Standards and Technology (NIST)
has established a testbed at its Gaithersburg, Md.,
headquarters
to help manufacturers improve the interoperability of their
dimensional measurement systems. The testbed is using
NIST-developed test methods and tools to verify that specific
equipment and software conform to new industry standards
designed to allow subsystems to "talk" to one
another even if they come from different manufacturers.
The
NIST
testbed was debuted at the International Manufacturing
Technology Show in Chicago, Sept. 8-15. The demonstration
features the use of two draft standard "languages" being
used to link together 10 major measuring components.
Successful
implementation of such standards throughout manufacturing
should save users time and money, avoid code rewriting
and measurement errors, and ultimately encourage a
more competitive
business environment with lower costs.
Media
Contact:
John
Blair, john.blair@nist.gov,
(301) 975-4261
Quick
Links
Two
NIST Scientists Earn Presidential Award
Two researchers
at the National Institute of Standards and Technology
(NIST) were among those honored as recipients of the
2003 Presidential Early Career Awards for Scientists
and Engineers on Sept. 9. NIST physicist Scott A.
Diddams was honored for his achievements in applying
new methods of optical frequency "combs"
to measure frequency with unprecedented accuracy,
an area that promises to produce the next-generation
of atomic clocks. NIST mechanical engineer Jon R.
Pratt was recognized for his contributions in the
fields of fundamental measurement science, manufacturing
research, and precision engineering, including realization
and dissemination of the unit of force at the micro-
and nano-scale.
The award
is the nation’s highest honor for professionals
at the outset of their independent research careers.
Fifty-seven researchers were recognized in a ceremony
presided over by John H. Marburger III, science advisor
to the President and director of the White House
Office
of Science and Technology Policy.
The
Presidential Early Career Awards for Scientists
and Engineers,
established in 1996, honor the most promising beginning
researchers in the nation within their fields.
Eight
federal departments and agencies annually nominate
scientists and engineers at the start of their
careers
whose work shows the greatest promise to benefit
the nominating agency’s mission. Participating
agencies award these beginning scientists and
engineers up
to five years of funding to further their research
in support of critical government missions.
For
more information, see www.whitehouse.gov/news/releases/2004/09/20040909-9.html.
NIST
to Support Cancer Nanotechnology Lab
As
part of a new $144.3 million, five-year initiative
to develop and apply nanotechnology to cancer research
and treatment, the National Institute of Standards
and Technology (NIST) and the National Cancer Institute
(NCI) have signed a new memorandum of understanding
and an interagency agreement. The agreement calls
for NIST to provide technology support to a key
component
of the initiative (known as NCI Alliance for Nanotechnology
in Cancer), the Nanotechnology Characterization
Laboratory
(NCL) at NCI's facility in Frederick, Md. The NCL
will perform and standardize the preclinical characterization
of nanomaterials developed by researchers from academia,
government and industry. The NCL will serve as
a national
resource and knowledge base for cancer researchers,
and facilitate the accelerated regulatory review
and
translation of nanomaterials and devices into the
clinical realm. For information about the NCI
Alliance
for Nanotechnology in Cancer, go to http://nano.cancer.gov.
September
Meetings Planned on Voting Systems
The
Technical Guidelines Development Committee, established
by the Help America Vote Act, will hold a series of three
meetings on the voluntary voting
standards
development process. Each day’s hearing will be
on a specific topic: Sept. 20, Computer Security and
Transparency; Sept. 21, Core Standards Requirements and
Testing; Sept. 22, Human Factors and Privacy. One hour
will be reserved each day for the public and the election
community to provide testimony on technical issues related
to these topics. The meetings and hearings will be held
at the National Institute of Standards and Technology
in Gaithersburg, Md. Advance registration is required
to attend the meeting. For further information, see www.vote.nist.gov.
October
Workshop Focuses on New Standard for Federal ID
The
National Institute of Standards and Technology (NIST)
will hold
a public workshop Oct. 7 at the Hilton Washington DC
North in Gaithersburg, Md., to discuss a new standard
for
secure and reliable forms of identification issued by the
federal government to its employees and contractors.
On
Aug. 27, 2004, the White House issued a presidential
directive calling for a mandatory, government-wide standard.
(The
directive is available at www.whitehouse.gov/news/releases/2004/08/20040827-8.html).
NIST will develop the standard as a Federal Information
Processing Standard tentatively titled “Personal
Identity Verification.” Topics to be discussed include
verification of identity using fingerprint and facial
images and personal
identity verification systems architecture, components,
algorithms, protocols and management. For further information
and to register for the meeting, see www.nist.gov/public_affairs/confpage/041007.htm.
CD-ROM
Trains Officials to Spot Scale/Meter Tampering
The
National Institute of Standards and Technology (NIST)
has just released a CD-ROM Audit Trail training course
for weights and measure officials. Audit trails are mechanisms
that many scale and meter manufacturers incorporate in
their electronic weighing and measuring machines. Audit
trails, commonly installed in gasoline pumps and supermarket
scanner scales, are used to monitor changes to the machines
that affect the accuracy of measurements. Weights and
measure officials increasingly use audit trail data to
spot tampering and fraudulent practices that hurt consumers
and competing, but honest, merchants.
The
CD-Rom includes narration, video and graphics to illustrate
correct
applications of weights and measure
standards, explain the principles behind audit trail data
acquisition and examples of how audit trail information
is accessed on different types of weighing and measuring
devices. The CD–ROM also includes interactive exercises
that enable users to test their knowledge as they work
through the course.
To
obtain a free copy of the Audit Trail Device Security
CD-Rom, contact NIST WMD, 100 Bureau Drive MS 2600, Gaithersburg,
MD 20888-2600, (301) 975-4004, fax: (301) 926-0647,
e-mail: owm@nist.gov.
(Return
to NIST News Page)
Editor:
Gail Porter
Date
created:09/13/04
Date updated:09/14/04
Contact: inquiries@nist.gov
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