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Displaying 801 - 825 of 882

Biogenic Contributions to Atmospheric Volatile Organic Compounds in Azusa, California

April 1, 2002
Author(s)
George A. Klouda, C. W. Lewis, D C. Stiles, J L. Marolf, W D. Ellenson, W A. Lonneman
An objective of the 1997 Southern California Ozone Study (SCOS97) was to provide an up-to-date assessment of the importance of biogenic emissions for tropospheric ozone production in the South Coast Air Basin. To this end ambient air samples were collected

Wide-Field X-Ray Microscopy with Kirkpatrick-Baez Optics

December 1, 2001
Author(s)
Terrence J. Jach, S M. Durbin, A S. Bakulin, David S. Bright, C B. Stagarescu, G Srajer, D. Haskel, J Pedulla
Modern technology permits us to fabricate Kirkpatrick-Baez (KB) multilayer optics with performance close to the theoretical limit. We have constructed a KB field-imaging microscope which operates in the x-ray energy range 6-10 keV with a field of view of

Distribution and Retention of 137 Cs in Sediments at the Hanford Site, Washington

September 1, 2001
Author(s)
J P. McKinley, Cynthia J. Zeissler, J M. Zachara, R J. Serne, Richard M. Lindstrom, H T. Schaef, R D. Orr
sium-137 and other contaminants have leaked from many of the single-shell storage tanks at the Hanford Site in southeastern Washington. The leakage was into sandy unconsolidated sediments consisting largely of quartz, plagioclase, micas, smectite, and

SRM 482 Revisited After 30 Years

August 1, 2001
Author(s)
Eric S. Windsor, R Carlton, Scott A. Wight, C Lyman
The National Institute of Standards and Technology's (NIST) Standard Reference Material (SRM) 482 was issued by The National Bureau of Standards (NBS) in 1969 and has been continuously available to the public for over 30 years [1]. The standard consists of

Isotopic Ratio Measurements by Time-of-Flight Secondary Ion Mass Spectrometry

July 1, 2001
Author(s)
Albert J. Fahey, S R. Messenger
Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is often considered synonymous with SIMS in the static limit where the ion fluence on the sample surface is so low that damage is negligible. For this same reason its use in measuring isotopic

Radioactive Particle Analysis by Digital Autoradiography

May 1, 2001
Author(s)
Cynthia J. Zeissler, Richard M. Lindstrom, J P. McKinley
We have been exploring ways to evaluate the activity of radioactive particles that have been detected by phosphor plate digital autoradiography based on photostimulated luminescence (PSL). A PSL system with 25υ pixel digitization has been applied to

Block Copolymer Thin Films: Physics and Applications

February 15, 2001
Author(s)
Michael J. Fasolka, A M. Mayes
A two-part review of research concerning block copolymer thin films is presented. The first section summarizes experimental and theoretical studies of the fundamental physics of these systems, concentrating upon the forces that govern film morphology. The

Fabrication and Electron Microprobe Characterization of Barium-Strontium-Titanate (BST) Films

February 1, 2001
Author(s)
Ryna B. Marinenko, J T. Armstrong, Debra L. Kaiser, Joseph J. Ritter, Peter K. Schenck, C P. Bouldin, J Blendell, Igor Levin
Barium strontium titanate (BST) thin films of varying composition and thickness (5nm to 400nm) on (100)Si or Pt/(100)Si substrates were measured using an electron microprobe analyzer with wavelength dispersive x-ray spectrometers. Most of the films were

Cluster Primary Ion Beam Secondary Ion Mass Spectrometry for Semiconductor Characterization

January 1, 2001
Author(s)
John G. Gillen, S V. Roberson, Albert J. Fahey, Marlon L. Walker, J Bennett, R Lareau
We are evaluating the use of polyatomic and cluster primary ion beams for characterization of semiconductor materials by secondary ion mass spectrometry using both magnetic sector and time-of-flight SIMS instruments. Primary ion beams of SF 5+, C 8- and

Highly Charged Ions

January 1, 2001
Author(s)
John D. Gillaspy
This article reviews some of the fundamental properties of highly charged ions, the methods of producing them (with particular emphasis on table-top devices), and their use as a tool for both basic science and applied technology. Topics discussed include

P-on-N Si Interband Tunnel Diode Grown by Molecular Beam Epitaxy

January 1, 2001
Author(s)
David S. Simons, P Chi, S L. Rommel, T E. Dillon, K D. Hobart, P E. Thompson, P R. Berger
Si interband tunnel diodes have been successfully fabricated by molecular beam epitaxy and room temperature peak-to-valley current ratios of 1.7 have been achieved. The diodes consist of opposing n- and p-type δ-doped injectors separated by an intrinsic Si

Preparation and Certification of K-411 Glass Microspheres

December 1, 2000
Author(s)
Ryna B. Marinenko, S V. Roberson, J S. Small, Barbara B. Thorne, Douglas H. Blackburn, D Kauffman, Stefan D. Leigh
The production and characterization of NBS K-411 glass microspheres in the 3-40 um range for certification as a NIST Standard Reference Material (SRM) are described. EDS quantitative analysis and heterogeneity evaluations of the microspheres were made with

Shape Factors of ISO 12103-A3 (Medium Test Dust)

November 1, 2000
Author(s)
Robert A. Fletcher, David S. Bright
A new derivative of Arizona sand, ISO Medium Test Dust, is coming into use as a liquid optical particle count calibrant. ISO Medium Test Dust and optical particle counters are used to test filtering efficiency. Particle shape plays a role in both filtering

Driven DNA Transport Into an Asymmetric Nanometer-Scale Pore

October 2, 2000
Author(s)
S. E. Henrickson, Martin Misakian, B Robertson, John J. Kasianowicz
To understand the mechanism by which individual DNA molecules partition into a nanometer-scale pore, we studied the concentration and voltage dependence of polynucleotide-induced current blockades of single a-hemolysin ionic channels. At fixed single

Amphibole Asbestos From Libby, Montana: Aspects of Nomenclature

October 1, 2000
Author(s)
A G. Wylie, Jennifer R. Verkouteren
Richterite-asbestos and winchite-asbestos are not listed in the Federal regulations governing asbestos. However, asbestiform winchite is found in the gangue at the Libby, Montana, vermiculite deposit, where asbestos-related diseases have been reported

Chemical Imaging With Scanning Near-Field Infrared Microscopy and Spectroscopy

October 1, 2000
Author(s)
Chris A. Michaels, Lee J. Richter, Richard R. Cavanagh, Stephan J. Stranick
The development of a scanning near-field microscope that utilizes infrared absorption as the optical contrast mechanism is described. This instrument couples the nanoscale spatial resolution of a scanning probe microscope with the chemical specificity of

Scanning Near-Field Infared Microscopy and Spectroscopy with a Broadband Laser Source

October 1, 2000
Author(s)
Chris A. Michaels, Lee J. Richter, Richard R. Cavanagh, Stephan J. Stranick
Near-field scanning optical microscopy (NSOM) is a powerful tool for the characterization of the optical properties of nanoscale objects, although pervasive artifacts often create difficulties in image interpretation. A three dimensional scanning NSOM
Displaying 801 - 825 of 882