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

Title: Quarterly progress report for Q1 FY06 for Complex Transient Events in Materials Studied Using Ultrafast Electron Probes and Terascale Simulation (FWP SCW0289)

Abstract

This quarter (Q1 FY06) marked the first time that the LLNL dynamic transmission electron microscope (DTEM) configuration had advanced to the point whereby it was possible to conduct in-situ experiments on specimens. DTEM improvements continue to progress at a rapid pace. We summarize important achievements in the following list: (1) Instrument performance and design improvements - (a) Reproducibly achieving >1 x 10{sup 7} e{sup -} per pulse. Adjustments in the cathode laser system design led to an improved quantum efficiency and electron yield per pulse. The current number of electrons in the pulse is sufficient for acquiring high quality, single-shot electron diffraction patterns. (b) Implementation of computer interface and Labview{reg_sign} programs for cathode and specimen drive alignment and cathode and pump laser trigger and delay settings. These controls provide a user friendly interface and ease in the experimental setup and implementation. (c) Cathode test chamber (offline test apparatus to asses photocathode design and laser induced photoemission) construction has been completed. (2) Notable instrument features brought into service - (a) Drive laser system was enhanced to improve beam shape and uniformity and to include continuous laser energy monitoring. The drive laser spot size on the specimen was also reduced from 70more » {mu}m x 110 {mu}m to 50 {mu}m x 75 {mu}m. (b) New phosphor coated face plate manufactured by TVIPS was installed. The sensitivity and signal noise ratio improved by factor 2 (sensitivity {approx}110 CCD counts/e{sup -} and signal to noise ratio {approx}5). (3) Experimental Progress - (a) First time-resolved experiment: observation of the {alpha} (hcp) to {beta} (bcc) phase transition in pure Ti films via single shot electron diffraction. Results of this experiment were published in the MRS Fall 2005 proceedings and are under review for article in the FEMMS proceedings, which will to be published in Journal of Material Science. See Experimental Results section for more on this experiment. (b) First single-shot image captured on the LLNL DTEM (image of diffraction grating replica with dispersed latex spheres): It is believed that this image holds the world's record for the highest combined spatial and temporal resolution in single shot image. The image was generated using a 1.5 ns-long electron pulse and has better than 20 nm spatial resolution.« less

Authors:
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
896008
Report Number(s):
UCRL-TR-217892
TRN: US201201%%624
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALIGNMENT; CATHODES; DIFFRACTION GRATINGS; ELECTRON DIFFRACTION; ELECTRON MICROSCOPES; ELECTRON PROBES; ELECTRONS; IMPLEMENTATION; LASERS; MONITORING; PHOSPHORS; PHOTOCATHODES; PHOTOEMISSION; PROGRESS REPORT; QUANTUM EFFICIENCY; REPLICAS; RESOLUTION; SIGNAL-TO-NOISE RATIO; SPATIAL RESOLUTION; TRANSIENTS

Citation Formats

Campbell, G. Quarterly progress report for Q1 FY06 for Complex Transient Events in Materials Studied Using Ultrafast Electron Probes and Terascale Simulation (FWP SCW0289). United States: N. p., 2005. Web. doi:10.2172/896008.
Campbell, G. Quarterly progress report for Q1 FY06 for Complex Transient Events in Materials Studied Using Ultrafast Electron Probes and Terascale Simulation (FWP SCW0289). United States. doi:10.2172/896008.
Campbell, G. Tue . "Quarterly progress report for Q1 FY06 for Complex Transient Events in Materials Studied Using Ultrafast Electron Probes and Terascale Simulation (FWP SCW0289)". United States. doi:10.2172/896008. https://www.osti.gov/servlets/purl/896008.
@article{osti_896008,
title = {Quarterly progress report for Q1 FY06 for Complex Transient Events in Materials Studied Using Ultrafast Electron Probes and Terascale Simulation (FWP SCW0289)},
author = {Campbell, G},
abstractNote = {This quarter (Q1 FY06) marked the first time that the LLNL dynamic transmission electron microscope (DTEM) configuration had advanced to the point whereby it was possible to conduct in-situ experiments on specimens. DTEM improvements continue to progress at a rapid pace. We summarize important achievements in the following list: (1) Instrument performance and design improvements - (a) Reproducibly achieving >1 x 10{sup 7} e{sup -} per pulse. Adjustments in the cathode laser system design led to an improved quantum efficiency and electron yield per pulse. The current number of electrons in the pulse is sufficient for acquiring high quality, single-shot electron diffraction patterns. (b) Implementation of computer interface and Labview{reg_sign} programs for cathode and specimen drive alignment and cathode and pump laser trigger and delay settings. These controls provide a user friendly interface and ease in the experimental setup and implementation. (c) Cathode test chamber (offline test apparatus to asses photocathode design and laser induced photoemission) construction has been completed. (2) Notable instrument features brought into service - (a) Drive laser system was enhanced to improve beam shape and uniformity and to include continuous laser energy monitoring. The drive laser spot size on the specimen was also reduced from 70 {mu}m x 110 {mu}m to 50 {mu}m x 75 {mu}m. (b) New phosphor coated face plate manufactured by TVIPS was installed. The sensitivity and signal noise ratio improved by factor 2 (sensitivity {approx}110 CCD counts/e{sup -} and signal to noise ratio {approx}5). (3) Experimental Progress - (a) First time-resolved experiment: observation of the {alpha} (hcp) to {beta} (bcc) phase transition in pure Ti films via single shot electron diffraction. Results of this experiment were published in the MRS Fall 2005 proceedings and are under review for article in the FEMMS proceedings, which will to be published in Journal of Material Science. See Experimental Results section for more on this experiment. (b) First single-shot image captured on the LLNL DTEM (image of diffraction grating replica with dispersed latex spheres): It is believed that this image holds the world's record for the highest combined spatial and temporal resolution in single shot image. The image was generated using a 1.5 ns-long electron pulse and has better than 20 nm spatial resolution.},
doi = {10.2172/896008},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Dec 27 00:00:00 EST 2005},
month = {Tue Dec 27 00:00:00 EST 2005}
}

Technical Report:

Save / Share:
  • In this quarter (Q2 FY06), the DTEM underwent a substantial reconfiguration of its laser systems. The cathode laser system was changed to provide greater numbers of electrons per pulse by lengthening the time duration of the pulse to 30 ns. The greater number of electrons per pulse has allowed us to acquire high quality pulsed images and diffraction patterns. The spatial resolution in the single pulsed image has been measured at better than 20 nm. The diffraction patterns are now more comparable to conventional electron microscope operation. Examples are found in the body of the report. We summarize important achievementsmore » in the following list: (1) Instrument performance and design improvements--(A) The laser system was changed for the cathode photoemission system (75 ns at 1053 nm wavelength converted to 30ns at 211 nm wavelength) to give longer electron pulses at the same current to yield more electrons per pulse. (B) New specimen drive laser constructed. (C) New computer monitored and controlled alignment systems installed for both laser systems to facilitate laser alignment through a user friendly computer interface. (2) Experimental Progress--(A) The spatial resolution of pulsed images was tested by imaging a cross-section of multilayer thin foils with 30 nm and 20 nm periods. Single pulse images were observed to have spatial resolution better than 20 nm. This combination of 20 nm spatial and 30 ns temporal resolution is thought to be highest combined spatial and temporal measurement ever made. (B) The quality of single pulse electron diffraction patterns have been improved to the point where differentiating the HCP from BCC patterns in Ti is substantially easier. The spatial coherence of the electron illumination on the specimen was improved to give much smaller diffraction spots in the pattern.« less
  • A method of assessing the uncertainty in the TOP event probability of a fault tree by a Monte Carlo simulation is presented. This approach is used to produce an empirical Bayes estimate of the probability intervals of TOP event unreliability. The Monte Carlo simulation used proceeds by propagating basic event probabilities, chosen randomly from input probability distributions through the tree, producing an empirical TOP event probability distribution (with associated confidence limits) after combining the results of many trials. The basic principles of this Monte Carlo approach are discussed. A new computer code, LIMITS, is presented and is used in severalmore » examples, and compared with the earlier SAMPLE code developed for the Reactor Safety Study. The results show that the LIMITS code is significantly faster due to an optimized sorting routing and that, in general, an even slightly faster code would be possible by the use of special random-number generators. Finally, sample input and output, and a listing of the program are provided for the reader who might wish to use the LIMITS code.« less
  • The content of a lecture at the senior-graduate level on materials characterization using ion, electron, and ion probes is amplified and extensively referenced. The emphasis of the report is compositional surface analysis using secondary ion mass spectrometry (SIMS), ion scattering spectrometry (ISS), Rutherford backscattering spectrometry (RBS), x-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES). The physical principles, experimental methods, advantages and limitations, and illustrative examples for each of the five methods are discussed. Composition in depth profiling using sputter ion etching is also described, including mechanisms, yields, rates, instrumentation, advantages, and limitations. Brief comments and literature citations are givenmore » for materials characterization using SIMS, ISS, RBS, AES, and XPS in corrosion, surface modification, surface segregration, thin films, and grain boundaries for various materials of interest in industrial materials science and engineering. Extensive references are provided as a guide for those desiring greater depth in the topical areas discussed.« less