Media Contact:
Michael
Baum , (301) 975-2763 
Optoelectronics
New NIST
Laser Measurement Service Has Users Beaming
Argon-fluoride
excimer lasers are shining brightly in both the medical and manufacturing
worlds. These lasers, which produce pulsed, ultraviolet radiation
at a wavelength of 193 nanometers, are commonly used in corneal
sculpting techniques such as photorefractive keratectomy and laser
in situ keratomileusis (abbreviated PRK and LASIK respectively)
that correct vision impairments. The excimer laser’s short wavelength
also makes it perfect for the high-resolution photo-lithography
needed to manufacture faster microprocessors and larger memory
chips.
The
explosive growth in ArF excimer laser use demands that better
measurement standards and techniques be available for calibrating
these instruments. Scientists Chris Cromer and Marla Dowell in
NIST’s
Optoelectronics Division, Boulder, Colo., have designed and
built two electrically calibrated laser calorimeters to accomplish
the task. Accurate assessments of the ArF excimer laser beam’s
energy are made in an enclosed environment using a specially designed,
beamsplitter-based measurement system.
For
technical information on this new 193-nanometer measurement service,
contact Marla Dowell,
MC 815.01, NIST, Boulder, Colo. 80303; (303) 497-7455.
Media
Contact:
Fred
McGehan (Boulder), (303) 497-3246
Information Technology
Two from
Down Under Now under MRA
Two
new countries have joined an international computer security arrangement
in a move that is expected to make it easier for American companies
to sell their products abroad.
Australia
and New Zealand joined the Common Criteria Mutual Recognition
Arrangement, a pact that establishes a concise but common language
specifying security requirements in information technology products
and systems.
The
original five nations—Canada, France, Germany, the United Kingdom
and the United States—launched the agreement just a year ago.
In the United States, the evaluation and validation program is
managed jointly by NIST and
the National
Security Agency.
The
signatory nations agree to recognize the results of security evaluations
conducted by each other’s accredited testing laboratories. This
eliminates the need for costly and time-consuming testing by different
countries. As the arrangement creates a standardized evaluation
process across borders, it fosters a barrier-free, worldwide market
for IT security products.
The
Management Committee of the Common Criteria Project unanimously
approved the application of Australia and New Zealand to become
full participants in the international arrangement. The approval
followed an assessment of the Australasian Information Security
Evaluation Programme, which is managed jointly by the Australian
Defense Signals Directorate and the New Zealand Government Communications
Security Bureau.
While
private-sector labs do the testing of computer security products,
the governments involved accredit the participating laboratories
and certify or validate the testing results.
Media
Contact:
Philip
Bulman , (301) 975-5661
Sensors
Study Sheds
Light on Degradation of Self-Assembled Monolayer Films
Self-assembled
monolayer films are the basis for promising new sensors and diagnostics
currently under commercial development for a variety of uses—everything
from detecting genetic diseases in humans to pinpointing pathogenic
microbes in food or water.
These
sensors are made of alkanethiol molecules that organize themselves
spontaneously on a gold surface to form a uniform crystalline
film just one molecule thick. Single-stranded DNA molecules are
tethered to this layer and used to latch onto complementary DNA
from a solution washed over the sensor.
Until
recently, self-assembled monolayers were thought to be stable
in an ordinary lab environment. However, studies have shown that
ozone in the air can degrade these monolayers by oxidizing the
thiol portion of the alkanethiol molecules.
A
team of NIST scientists examined this process using scanning tunneling
microscopy and photoelectron spectroscopy. To follow the time
evolution of the reaction, they exposed monolayer films to increasing
doses of pure ozone while recording STM data. This revealed that
ozone attacks the crystalline monolayers preferentially at the
network of domain boundaries between the molecules. As ozone exposure
increases, the reaction spreads into the domains.
The
images also provided evidence of an unexpected occurrence: the
crystalline monolayer melts and forms either a liquid or non-crystalline
solid.
The
NIST study points to possible strategies to improve the monolayer’s
stability in ozone, such as decreasing the density of the domain
boundaries or decorating the boundaries with molecules that are
ozone-inert. The study will be reported in an upcoming issue of
the Journal of the American Chemical Society.
For
more information, contact Gregory
E. Poirier, (301) 975-2603, or check out www.nist.gov/sams
on the World Wide Web.
Media
Contact:
Linda
Joy, (301) 975-4403
Materials
Long-Distance
Weld Monitoring Now Feasible
Quality
control has gone remote. In a recent paper, Timothy P. Quinn,
a researcher in NIST’s
Materials Reliability Division, Boulder, Colo., reports that
he monitored the quality of welds made in Gaithersburg, Md., via
the Internet. The welds joined a mounting bracket to the shaft
of an automobile suspension strut. A pair of two-second welds
were made with an approximately one-second delay between welds.
The monitoring was done through the arc sensing monitor (known
as ASM), a through-the-arc sensing system.
“In
both cases, the network speed was adequate to transmit the data
between welds and have the ASM be ready to process the next weld,”
Quinn reports.
Approximately
three kilobits of data need to be transmitted for each second
of weld. The web server, the engineering workstation and the database
server all can run on a single personal computer.
Quinn
says that remote monitoring has the advantage of allowing informed
decisions to be quickly made—from anywhere—about maximizing a
welding station’s productivity or solving operating problems that
occur. The only requirement is that a reliable Transmission Control
Protocol and Internet Protocol (known as TCP/IP) network must
be installed in the factory.
For
a copy of the paper, 43-99, “Internet Based Management of Data
from Welding Sensors,” contact Sarabeth
Harris, MC 104, NIST, Boulder, Colo. 80303-3337.
Media
Contact:
Fred
McGehan (Boulder) , (303) 497-3246
Builidngs
NIST Turns
Over CMRL Management after 70 Years
NIST
is transferring management of the Construction Materials Reference
Laboratory to the private sector after 70 years of growth. At
the same time, the CMRL’s link to NIST research is being strengthened.
Stewardship
of the two CMRL program components, the Cement and Concrete Reference
Laboratory (abbreviated CCRL) and the American Association of
State Highway and Transportation Officials Materials Reference
Laboratory (abbre-viated AMRL), changes this month. Taking over
for NIST are the sponsoring organizations: AASHTO for AMRL and
the American Society for Testing and Materials for CCRL. Both
the CCRL and AMRL will continue to operate from NIST.
Launched
in 1929 because of concerns about the quality of cement used in
the construction of federal facilities, the CMRL now includes
more than 1,200 laboratories that test materials used by the construction
industry. Participants use a variety of AASHTO and ASTM standard
test methods to help assure that high-quality materials will be
the norm in the American construction industry. These labs test
everything from concrete to asphalt and serve many private-sector
firms, as well as state and local governments.
Participation
in the CMRL programs is voluntary. They have grown steadily over
the decades to keep up with the demand for quality assurance in
the testing of building materials such as concrete, cement, soil
and asphalt. The CMRL now carries out on-site assessment programs
for over 700 testing labs. It evaluates test equipment, identifies
testing deficiencies and supplies proficiency samples.
Currently,
the CMRL distributes more than 13,000 proficiency samples annually
to laboratories in the United States, Canada, Mexico and more
than a dozen other countries. The CMRL’s role in the construction
industry is significant because inadequate testing can lead to
good materials being rejected, poor materials being accepted,
construction delays and even structural failures.
Participating
laboratories should not see any significant changes in the CMRL
or either of its components as a result of the management change.
For
more information, contact James
Pielert, NIST, 100 Bureau Drive, Stop 8622, Gaithersburg,
Md. 20899-8622, (301) 975-6704.
Media
Contact:
Philip
Bulman , (301) 975-5661
Editor:
Michael Newman
HTML conversion: Crissy
Robinson
Last updated: October 13, 1999
Go back to NIST News Page