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Title: Estimation of the effective temperature of field evaporated ions in a laser-pulsed atom probe

Abstract

No abstract prepared.

Authors:
 [1];  [2];  [2];  [3];  [3]
  1. ORNL
  2. Imago Scientific Instruments, Madison, WI
  3. National Institute for Materials Science, Tsukuba, Japan
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Shared Research Equipment Collaborative Research Center
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
936024
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: Microscopy & Microanalysis 2007, Fort Lauderdale, FL, USA, 20070806, 20070809
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; LASERS; PULSE TECHNIQUES; PROBES; ATOMS; IONIZATION

Citation Formats

Miller, Michael K, Larson, David J., Olson, J. D., Ohkubo, T., and Hono, K. Estimation of the effective temperature of field evaporated ions in a laser-pulsed atom probe. United States: N. p., 2007. Web.
Miller, Michael K, Larson, David J., Olson, J. D., Ohkubo, T., & Hono, K. Estimation of the effective temperature of field evaporated ions in a laser-pulsed atom probe. United States.
Miller, Michael K, Larson, David J., Olson, J. D., Ohkubo, T., and Hono, K. Mon . "Estimation of the effective temperature of field evaporated ions in a laser-pulsed atom probe". United States. doi:.
@article{osti_936024,
title = {Estimation of the effective temperature of field evaporated ions in a laser-pulsed atom probe},
author = {Miller, Michael K and Larson, David J. and Olson, J. D. and Ohkubo, T. and Hono, K.},
abstractNote = {No abstract prepared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Conference:
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  • Three methods are discussed for determining the field emitter temperature during laser irradiation in the recently developed Pulsed Laser Atom Probe. A procedure based on the reduction of the lattice evaporation field with increasing emitter temperature is found to be the most convenient and reliable method between 60 and 500 K. Calibration curves (plots of the evaporation field versus temperature) are presented for dc and pulsed field evaporation of W, Mo, and Rh. These results show directly the important influence of the evaporation rate on the temperature dependence of the evaporation field. The possibility of a temperature calibration based onmore » the ionic charge state distribution of field evaporated lattice atoms is also discussed. The shift in the charge state distributions which occurs when the emitter temperature is increased and the applied field strength is decreased at a constant rate of evaporation is shown to be due to the changing field and not the changing temperature. Nevertheless, the emitter temperature can be deduced from the charge state distribution for a specified evaporation rate. Charge state distributions as a function of field strength and temperature are presented for the same three materials. Finally, a preliminary experiment is reported which shows that the emitter temperature can be determined from field ion microscope observations of single atom surface diffusion over low index crystal planes. This last calibration procedure is shown to be very useful at higher temperatures (>600 K) where the other two methods become unreliable.« less
  • A high resolution pulsed-laser time-of-flight atom-probe field ion microscope has been developed which is a surface analytical tool of single atom detection sensitivity. It is a mass and energy analyzer with a resolution and accuracy of --5 parts in 10/sup 5/, and an ion reaction time measuring device of 20 fs time resolution. This system can be used to analyze surface atoms one by one and surface atomic layers one by one also. The application of this system to study solid surfaces are described.
  • The pulsed-laser and imaging atom-probe are emerging as powerful tools for the study of surface chemical reactions. Detailed studies of molecular processes such as thermal dissociation provide valuable insight into the basic interactions governing a reaction sequence, and extended studies should lead to a complete understanding of simple surface reactions such as CO oxidation, methanation, etc. The combination of these techniques with a high-pressure reactor add a new dimension to the study of surface reactions, and, as the CO oxidation investigation reported here demonstrates, information with direct applicability to commercially important catalytic reactions can be obtained.
  • A new approach to time-of-flight atom-probe mass spectroscopy was introduced in 1979 with the development of the photon induced field ionization mass spectrometer and the pulsed laser atom-probe. These techniques, which were independently developed, differed from conventional atom-probes in that the field evaporation of surface species was initiated with a short duration laser pulse and a dc electric field, rather than a high voltage electrical pulse. This approach has been shown to have several advantages. Two recent applications which exploit some of these advantages are described. The first, a study of insulating glasses, demonstrates the applicability of the pulsed lasermore » atom-probe to high resistivity materials. The second, a study of the field dependence of the charge state distributions of field evaporated ions, utilizes the capability of the pulsed laser technique to carry out field evaporation measurements as a function of the applied electric field. The results of this latter study have been found to be consistent with recently proposed postionization models of field evaporation.« less
  • Two powerful pulsed-laser atom-probes have been developed to study gas-surface interactions such as field adsorption of gases at low temperature, and mechanisms of formation of NH/sub 3/ and H/sub 3/ on metal surfaces. Information obtained includes adsorption energy, material specificities of these reactions, desorption sites, and the reaction intermediates, etc. This information is vital to our microscopic understanding of technologically important areas of research such as surface reactivity in heterogeneous catalysts, corrosion and wear of materials, and many other areas.