Journal of Research of the National Institute of Standards and Technology articles from July 2002

Journal of Research of the National Institute of Standards and Technology archives from July 2002

Diffractive optics from self-assembled DNA.
July 1, 2002... An algorithm is presented for assembling tiles into a variable spaced grating, the one-dimensional analog of a Fresnel zone plate. The algorithm supports multi-level gratings. The x-ray properties of such a grating, assumed to be constructed...

Electron-impact cross sections for dipole- and spin-allowed excitations of hydrogen, helium, and lithium.
July 1, 2002... Electron-impact excitation cross sections are presented for the dipole- and spin allowed transitions from the ground states to the tip [P.sup.2] states for hydrogen and lithium, and to the 1snp [P.sup.1] P states for helium, n = 2 through 10....

Quantitating fluorescence intensity from fluorophores: practical use of MESF values.
July 1, 2002... The present work uses fluorescein as the model fluorophore and points Out critical steps in the use of MESF (Molecules of Equivalent Soluble Fluorophores) values for quantitative flow cytometric measurements. It has been found that emission...

Optical diffraction in close proximity to plane apertures. I. boundary-value solutions for circular apertures and slits.
July 1, 2002... In this paper the classical Rayleigh-Sommerfeld and Kirchhoff boundary-value diffraction integrals are solved in closed form for circular apertures and slits illuminated by normally incident plane waves. The mathematicla expressions obtained...

Development of a tunable LED-based colorimetric source.
July 1, 2002... A novel, spectrally tunable light-source utilizing light emitting diodes (LEDs) for radiometric, photometric, and colorimetric applications is described. The tunable source can simulate standard sources and can be used as a transfer source to...

Conventional cells--the last step toward general acceptance of standard conventional cells for the reporting of crystallographic data.
July 1, 2002... In 1969, a seminal section on reduced forms and conventional cells was published in the International Tables for X-Ray Crystallography. The section contains a table that gives a metric classification of the 44 reduced forms. In 2001, this table...

NIST's Role Based Access Control research saves industry $295 million. (General Developments).
July 1, 2002... A new independent economic impact study conducted by the Research Triangle Institute (RTI) conservatively estimates that NIST's Role Based Access Control (RBAC) research has saved U.S. industry $295 million and accelerated industrys adoption of...

NIST researchers demonstrate high-speed thermal imaging system. (General Developments).(Brief Article)
July 1, 2002... NIST researchers used a high-speed thermal imaging system to study transient thermal characteristics of microhotplate structures. Their studies demonstrated the importance of the microhotplate heat-spreading layer in obtaining a uniform dynamic...

Adsorption of fuel odorants provides clue to fading. (General Developments).(Brief Article)
July 1, 2002... Sulfur compounds, specifically thiols and alkylsulfides, are added to fuel gas to give the fuel distinctive odors that alert consumers to leaks. Over time, however, odorant concentration in fuel gases may decrease below olfactory thresholds....

Process to remove carbonyl sulfide from LPG. (General Developments).
July 1, 2002... A patent has been issued (Patent No. 6,334,949, Jan. 1, 2002) to two NIST scientists for a process that selectively removes carbonyl sulfide, a potentially problematic impurity, from liquefied petroleum gas (LPG). NIST scientists in Boulder...

NIST helps develop first IEEE wireless personal area network standard. (General Developments).
July 1, 2002... NIST contributed significantly to a new standard for wireless personal area networks (WPANs) approved by the Institute of Electrical and Electronics Engineers (IEEE) on March 21, 2002. The approval of IEEE 802.15.1 was the long-awaited formal...

NIST reviews security of Indian Trust Management, department of the interior. (General Developments).(Brief Article)
July 1, 2002... On April 1, 2002, NIST's Computer Security Expert Assist Team (CSEAT) delivered the CSEAT Indian Trust Management (ITM) draft high-risk program review report to the Associate Deputy Secretary of the Department of the Interior. ITM is...

New statistic addresses long-term stability. (General Developments).(Brief Article)
July 1, 2002... The measurement of the long-term stability of clocks and oscillators has been a long-standing problem for science and industry. The Allan deviation and another statistic called total deviation both require data runs twice as long as the desired...

Light scattering by metallic particles on silicon wafers. (General Developments).(Brief Article)
July 1, 2002... Light scattering is used by semiconductor manufacturers to inspect silicon wafers for particulates, defects, and surface roughness. Since a particle's size determines its potential to cause device failure, it is critical to be able to...

Self-Study Manual now available on Compact Disc. (General Developments).(Brief Article)
July 1, 2002... The Self-Study Manual on Optical Radiation Measurements has proven to be a valuable and useful reference in the fields of radiometry and photometry. This series of eight documents was published from 1977 to 1985 as NBS Tech Notes 910-1 through...

Photoassociation in a Bose-Einstein condensate. (General Developments).(Brief Article)
July 1, 2002... Two colliding atoms can absorb a photon and be photo-associated into an excited, diatomic molecule. NIST researchers investigated the fundamental rate at which this process can take place in a Bose-Einstein condensate (BEC) and demonstrated...

Ultracold gases spin a winding yarn. (General Developments).(Brief Article)
July 1, 2002... Experiments on quantum gases continue to yield amazing and counter-intuitive results. In autumn 2001, researchers at NIST found that a non-condensed Bose-Einstein gas could display spatial segregation of internal spin states, even though the...

NIST researches improve high-resistance measurement capability. (General Developments).(Brief Article)
July 1, 2002... A NIST scientist has developed a new technique that enables more accurate scaling from the primary NIST quantum Hall resistance standard to high resistance levels of 1 M[ohm] and above. The technique exploits a unique property of the quantum...

NIST leads creation of two new IEC superconductivity standards. (General Developments).(Brief Article)
July 1, 2002... Two new intemational standards on superconductivity were recently published by the International Electro-technical Commission (IEC) Technical Committee 90 (TC 90). The documents are: * IEC 61788-4 Superconductivity--Part 4: Residual...

Sprinklered versus non-sprinklered dormitory room fires. (General Developments).(Brief Article)
July 1, 2002... NIST has compiled a 9 minute video of fires in two college dormitory rooms, one equipped with sprinklers and the other without sprinklers. Small fires were ignited in a wastebasket between the desk and bed in each of the two fully-furnished...

Simulation of multiple fatality house fire in Keokuk, Iowa. (General Developments).(Brief Article)
July 1, 2002... This report, Simulation of the Dynamics of a Fire in a Two-Story Duplex--Iowa, Dec. 22, 1999 (NISTIR 6854), describes the re-creation of a fire in a two-story duplex house in Iowa which claimed the lives of three children and three...

New standard for Thread Wire Measurement. (General Developments).(Brief Article)
July 1, 2002... A new standard for measurement of thread wires has just been published. The standard, ASME B89.1.17, Measurement of Thread Measuring Wires, was developed under the leadership of a NIST guest researcher. The new standard will establish uniform...

Temperature gradient focusing in microfluidic channels. (General Developments).(Brief Article)
July 1, 2002... NIST scientists have developed a new method to concentrate and separate chemical species in micro-fluidic channels. Microfluidic, or "lab-on-a-chip," devices are miniaturized chemical and biochemical analysis systems that one day may replace...

High accuracy technique revolutionizes platinum group metals assay. (General Developments).(Brief Article)
July 1, 2002... NIST researchers have developed a high performance approach to the measurement of elemental composition using inductively coupled plasma optical emission spectroscopy. This technique uses an innovative experiment design coupled with a novel...

Fabricating planar nanoparticle assemblies with number density gradients. (General Developments).
July 1, 2002... Nanoparticle-based structures are envisioned to play an important role in futuristic devices such as single-electron tunneling-based computer chips, high-density information storage devices, and other commercially-important applications such as...

Simple model system for fabrication of integrated circuit interconnects. (General Developments).
July 1, 2002... Electrodeposition has recently and unexpectedly evolved with a major role in on-chip metallization, which provides the interconnects between transistors, etc. in an integrated circuit. The understanding of copper deposition for this particular...

Scanned probe oxidation given unique recognition. (General Developments).(Brief Article)
July 1, 2002... Scanned probe oxidation (a.k.a. local oxidation or nanooxidation), pioneered several years ago by NIST, has been given its own unique code, 81.16.Pr, in the American Institute of Physics recently updated Physics and Astronomy Classification...

Leading NIST publication cited. (General Developments).(Brief Article)
July 1, 2002... The Review of Scientific Instruments, which is widely regarded as the preeminent journal describing scientific instrumentation, is a frequent vehicle for the dissemination of NIST-developed measurement methodology. Recently, a scientist at the...

NIST contributes to report on Protecting Buildings from terrorist attacks. (General Developments).(Brief Article)
July 1, 2002... NIST participated in the development of "Guidance for Protecting Building Environments from Airborne Chemical, Biological, or Radiological Attacks." The report, published by the National Institute of Occupational Safety and Health, was...

Corrective refractive optics sharpens focus of SANS instrument. (General Developments).(Brief Article)
July 1, 2002... Pioneering work done at the NIST Center for Neutron Research (NCNR), in collaboration with a private company, demonstrated that focusing a cold neutron beam with multiple biconcave lenses is a practical means of improving the resolution of...

Crystal structures and phase equilibria of ceramics for low temperature co-fired ceramics. (General Developments).(Brief Article)
July 1, 2002... The primary technology drivers for wireless consumer devices and computer applications are miniaturization, higher frequency, lower operating voltages, reduction of component part count, and increased functionality. For example, multiband...

New approach to fatigue testing of chip-level interconnects. (General Developments).(Brief Article)
July 1, 2002... Researchers at NIST, in collaboration with the Max-Planck-Institute for Metals Research, have been conducting fatigue testing of thin aluminum and copper films on silicon-based substrates through the application of high current density ac...

Monte Carlo simulations completed for sem resolution study. (General Developments).(Brief Article)
July 1, 2002... In June, a NIST scientist completed Monte Carlo simulations of scanning electron microscope (SEM) imaging of resist lines on silicon. These represent the first part of a study being performed at the behest of International SEMATECH on the...

NIST expands UV optical material characterization facility. (General Developments).(Brief Article)
July 1, 2002... NIST has completed a series of measurements to determine the damage threshold and lifetime of optical materials under intense ultraviolet (UV) radiation produced by excimer lasers. Using a capability developed by a NIST scientist and NIST guest...

Laser-focused nanolines link the micro- and nano-worlds. (General Developments).(Brief Article)
July 1, 2002... A collaboration of scientists from NIST and the University of Nijmegen (Netherlands) has shown that two sets of nearly-identical nanolines created by laser-focused atomic deposition can interfere with each other to form a metrologically...

NIST hosts Conference on Designs for Generalized Linear Models. (General Developments).(Brief Article)
July 1, 2002... Celebrating the 30th anniversary of the Nelder and Wedderburn paper introducing generalized linear models (GLMs), NIST hosted the Conference on Designs for Generalized Linear Models in Gaithersburg in April 2002. The primary goal of the...

Photoionization-of-[CO.sub.2] database available online. (General Developments).(Brief Article)
July 1, 2002... NIST has made available on the Web a database containing photoionization efficiency, vibrational branching ratios, and asymmetry parameters in the photoionization of [CO.sub.2] in the region between 65 nm and 84 nm. The study of [CO.sub.2]...

Blackbody sources calibrated at the LBIR facility. (General Developments).(Brief Article)
July 1, 2002... The Low-Background Infrared (LBIR) facility provides means to calibrate low power thermal-infrared sources (blackbodies). Since all material gives off less infrared radiation as it gets cooler, the inner walls of the LBIR facility are cooled...

NIST releases updated Reference Data Set to fight computer crime. (General Developments).(Brief Article)
July 1, 2002... NIST recently released an updated National Software Reference Library (NSRL) Reference Data Set to assist the law enforcement community in fighting crimes involving computers. The NSRL encompasses a repository of all types of software,...

NIST's noise-temperature measurement service now available at continuous frequencies from 1 GHz to 65 GHz. (General Developments).(Brief Article)
July 1, 2002... NIST has completed the testing of the 1 GHz to 4 GHz units of its coaxial radiometer (NFRad) and has reopened the noise-temperature measurement service for that frequency band. This marks the completion of a multiyear effort to restore and...

NIST researchers demonstrate stacked Josephson junction arrays using [MoSi.sub.2] barriers. (General Developments).(Brief Article)
July 1, 2002... Researchers at NIST have demonstrated that molybdenum di-silicide is an excellent normal-metal material for junction barriers in high-density arrays of superconductor-normal-metal-superconductor (SNS) Josephson junctions. For the past few years...

New pulsed laser deposition technique speeds search for high-tech thin films. (General Developments).(Brief Article)
July 1, 2002... A new rapid prototyping technique developed by two NIST scientists could speed up the search for thin films with properties optimized for next-generation memory devices and wireless communications circuits. The novel method--called dual-beam,...

One-dimensional "pencil" disorder discovered for a class of intermetallic compounds. (General Developments).
July 1, 2002... Deviations of atoms from an average crystal structure caused by structural distortions, chemical ordering, or the presence of defects cause diffuse intensity in scattering experiments. The diffuse scattering is usually difficult to detect by...

NIST produces two new wavelength calibration standards for the wavelength division multiplexing L-band. (Standard Reference Materials).(Brief Article)
July 1, 2002... NIST has developed two wavelength calibration transfer standards for the new L-band of wavelength division multiplexed (WDM) optical fiber communication systems. These standards, based on the absorption spectrum of carbon monoxide, are now...