skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: An Ion Chamber Dedicated to Carbon NEXAFS: Removal of High-Order X-Rays and Reliable Flux Measurement

Abstract

The difficulty of performing a reliable carbon NEXAFS measurement for thin films and adsorbate systems has long been recognized. The difficulty is typically related to lower S/B, carbon buildup in beamline optics, dirty mesh, presence of the high-order x-rays, etc. To alleviate the experimental difficulty, we have constructed an intensity-monitoring ion chamber situated between the beamline and sample chamber. The ion chamber is filled with argon up to a working pressure of 10-3 Torr and terminated with 0.1 {mu}m thick Ti foils at both ends. Titanium foils and the filled argon gas effectively remove the high-order x-rays. Consequently, the data are acquired with predominant 1st-order x-rays and thus free of the aforementioned interference, leading to a more reliable data analysis.

Authors:
; ;  [1]
  1. National Synchrotron Radiation Research Center, Hsinchu, Taiwan 30076 (China)
Publication Date:
OSTI Identifier:
21054780
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 882; Journal Issue: 1; Conference: XAFS13: 13. international conference on X-ray absorption fine structure, Stanford, CA (United States), 9-14 Jul 2006; Other Information: DOI: 10.1063/1.2644705; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ABSORPTION SPECTROSCOPY; ARGON; BEAM MONITORING; BEAM OPTICS; BEAM PRODUCTION; CARBON; DATA ANALYSIS; FINE STRUCTURE; FOILS; INTERFERENCE; IONIZATION CHAMBERS; PHOTON BEAMS; THIN FILMS; TITANIUM; X RADIATION; X-RAY SPECTROSCOPY

Citation Formats

Fan, L.-J., Yang, Y.-W., and Lee, Kaidee. An Ion Chamber Dedicated to Carbon NEXAFS: Removal of High-Order X-Rays and Reliable Flux Measurement. United States: N. p., 2007. Web. doi:10.1063/1.2644705.
Fan, L.-J., Yang, Y.-W., & Lee, Kaidee. An Ion Chamber Dedicated to Carbon NEXAFS: Removal of High-Order X-Rays and Reliable Flux Measurement. United States. doi:10.1063/1.2644705.
Fan, L.-J., Yang, Y.-W., and Lee, Kaidee. Fri . "An Ion Chamber Dedicated to Carbon NEXAFS: Removal of High-Order X-Rays and Reliable Flux Measurement". United States. doi:10.1063/1.2644705.
@article{osti_21054780,
title = {An Ion Chamber Dedicated to Carbon NEXAFS: Removal of High-Order X-Rays and Reliable Flux Measurement},
author = {Fan, L.-J. and Yang, Y.-W. and Lee, Kaidee},
abstractNote = {The difficulty of performing a reliable carbon NEXAFS measurement for thin films and adsorbate systems has long been recognized. The difficulty is typically related to lower S/B, carbon buildup in beamline optics, dirty mesh, presence of the high-order x-rays, etc. To alleviate the experimental difficulty, we have constructed an intensity-monitoring ion chamber situated between the beamline and sample chamber. The ion chamber is filled with argon up to a working pressure of 10-3 Torr and terminated with 0.1 {mu}m thick Ti foils at both ends. Titanium foils and the filled argon gas effectively remove the high-order x-rays. Consequently, the data are acquired with predominant 1st-order x-rays and thus free of the aforementioned interference, leading to a more reliable data analysis.},
doi = {10.1063/1.2644705},
journal = {AIP Conference Proceedings},
number = 1,
volume = 882,
place = {United States},
year = {Fri Feb 02 00:00:00 EST 2007},
month = {Fri Feb 02 00:00:00 EST 2007}
}
  • Probing surface order as well as the degree of structural modification in carbon nanotube systems is of fundamental importance for incorporation of these materials into practical functional devices. The current study pertains to the analysis of the surface order of vertically-aligned single-walled and multi-walled carbon nanotube arrays of varying length and composition by means of near-edge X-ray fine structure spectroscopy (NEXAFS). Both NEXAFS and scanning electron microscopy (SEM) studies concluded that the nanotubes in these samples were oriented vertically to the plane of the surface. However, NEXAFS polarization analysis provided a more quantitative and nuanced description of the surface structure,more » indicative of far less localized surface order, an observation partially attributed to misalignment and bending of the tubes. Moreover, it was demonstrated by NEXAFS that the surface order of the arrays was imperfect and relatively independent of the height of the nanotube arrays. In addition, we have shown that NEXAFS can be used to correlate the extent of chemical functionalization and oxygenation with disruption of the electronic and physical structure of nanotubes embedded in array motifs.« less
  • Imagine using a real-time virtual simulator to learn to fly a space shuttle or rebuild your car's transmission without touching a piece of equipment or getting your hands dirty. Now, apply this concept to learning how to operate and control a state-of-the-art, electricity-producing power plant capable of carbon dioxide (CO{sub 2}) capture. That's what the National Energy Technology Laboratory's (NETL) Advanced Virtual Energy Simulation Training and Research (AVESTAR) Center (www.netl.doe.gov/avestar) is designed to do. Established as part of the Department of Energy's (DOE) initiative to advance new clean energy technology for power generation, the AVESTAR Center focuses primarily on providingmore » simulation-based training for process engineers and energy plant operators, starting with the deployment of a first-of-a-kind operator training simulator for an integrated gasification combined cycle (IGCC) power plant with CO{sub 2} capture. The IGCC dynamic simulator builds on, and reaches beyond, conventional power plant simulators to merge, for the first time, a 'gasification with CO{sub 2} capture' process simulator with a 'combined-cycle' power simulator. Based on Invensys Operations Management's SimSci-Esscor DYNSIM software, the high-fidelity dynamic simulator provides realistic training on IGCC plant operations, including normal and faulted operations, as well as plant start-up, shutdown and power demand load changes. The highly flexible simulator also allows for testing of different types of fuel sources, such as petcoke and biomass, as well as co-firing fuel mixtures. The IGCC dynamic simulator is available at AVESTAR's two locations, NETL (Figure 1) and West Virginia University's National Research Center for Coal and Energy (www.nrcce.wvu.edu), both in Morgantown, W.Va. By offering a comprehensive IGCC training program, AVESTAR aims to develop a workforce well prepared to operate, control and manage commercial-scale gasification-based power plants with CO{sub 2} capture. The facility and simulator at West Virginia University promotes NETL's outreach mission by offering hands-on simulator training and education to researchers and university students.« less