U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Search Publications by: William E. Wallace (Fed)

Search Title, Abstract, Conference, Citation, Keyword or Author
Displaying 51 - 75 of 110

Recent Advances in Quantitative Synthetic-Polymer Mass Spectrometry at NIST

January 1, 2004
Author(s)
William E. Wallace, Charles M. Guttman
Commensurate with NIST s mission to advance the state of quantitative measurement science we have worked to develop a method to determine absolute molecular mass distribution of synthetic polymers by mass spectrometry. Work has centered on using matrix

Certification of a Polystyrene Synthetic Polymer, SRM 2888

November 1, 2003
Author(s)
Charles M. Guttman, William R. Blair, B M. Fanconi, R J. Goldschmidt, William E. Wallace, S Wetzel, David L. VanderHart
The certification of a polystyrene standard reference material, SRM 2888, is described. The M w of SRM 2888 was determined by light scattering to be 7.19 x 10 +3 g/mol with a sample standard deviation of 0.14 x 10 +3 g/mol. A combined expanded uncertainty

A Direct Comparison of Surface and Bulk Chain-Relaxation in Polystyrene

September 1, 2003
Author(s)
Wen-Li Wu, S Sambasivan, C M. Wang, William E. Wallace, Jan Genzer, Daniel A. Fischer
Near-edge x-ray absorption fine structure (NEXAFS) spectroscopy was used to meausre simultaneously the relaxation rates of polystyrene (PS) molecules at the free surface and in the bulk. The samples were uniaxially stretched and annealed at temperatures

MALDI-TOF MS Characterization of Covalent Cationized Polyethylene

August 1, 2003
Author(s)
Sheng Lin-Gibson, D L. Brunner, David L. VanderHart, Barry J. Bauer, B M. Fanconi, Kathleen M. Flynn, William E. Wallace
MALDI-TOF MS generally uses metal salts to cationize synthetic polymers, such as polystyrene. However, reduced analyte signal often results from complications during the metal ionization processes in the gas phase including competition between the analyte

Resonant Soft X-Ray Photofragmentation of Propane

July 1, 2003
Author(s)
William E. Wallace, Daniel A. Fischer
A comparison was made between the mass spectra of propane (CH6d3^CH 2CH 3) for resonant soft X-ray photofragmentation and electron-impact ionization. The soft X-ray photon energy was tuned to 287.7 eV to promote Auger relaxations from the C-H bonds (1s _>

Quantitative Synthetic Polymer Mass Spectrometry Workshop

February 1, 2003
Author(s)
William E. Wallace, Charles M. Guttman, S D. Hanton
Mass spectrometry is a rapidly evolving measurement technique for synthetic polymers. It holds the promise of providing not only absolute molecular mass distributions but also quantitative end-group and repeat-unit composition, and structural information

Correlation of Molecular Orientation with Adhesion at Polystyrene/Soild Interfaces

September 1, 2002
Author(s)
P T. Wilson, Lee J. Richter, William E. Wallace, Kimberly A. Briggman, John C. Stephenson
Vibrationally resonant sum-frequency generation (VR-SFG) has been used to characterize the molecular orientation of the phenyl groups at the interface between polystyrene (PS) films and surface-modified glass substrates. Both the interface structure and

MALDI MS Characterization of Covalent Cationized Polyethylene

August 1, 2002
Author(s)
Sheng Lin-Gibson, D L. Brunner, David L. VanderHart, Barry J. Bauer, B M. Fanconi, Kathleen M. Flynn, William E. Wallace
Polyolefins, saturated hydrocarbon polymers such as polyethylene (PE) and polypropylene, are, by production volume, the most widely used of all A new method for the mass spectrometry of saturated polyolefins whereby an organic cation is covalently bonded

Optimizing the Covalent Cationization Method for the Mass Spectrometry of Polyolefins

August 1, 2002
Author(s)
Sheng Lin-Gibson, L Brunner, David L. VanderHart, Barry J. Bauer, B M. Fanconi, Charles M. Guttman, William E. Wallace
Previously a new method was introduced for the mass spectrometry of polyolefins whereby an organic cation is covalently bonded to the polymer to produce the necessary ionization for the creation of intact gas?phase macromolecules by matrix-assisted laser

Advanced Numerical Methods for Polymer Mass Spectral Data Analysis

July 1, 2002
Author(s)
William E. Wallace, Charles M. Guttman, Anthony J. Kearsley, Javier Bernal
A mathematical algorithm is presented that accurately locates and calculates the area beneath peaks using only reproducible mathematical operations and a single user-selected sensitivity parameter.

Data Analysis Methods for Synthetic Polymer Mass Spectrometry: Autocorrelation

February 1, 2002
Author(s)
William E. Wallace, Charles M. Guttman
Autocorrelation is shown to be useful in describing the periodic patterns found in high-resolution mass spectra of synthetic polymers. Examples of this usefulness are described for a simple linear homopolymer to demonstrate the method fundamentals, a