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You searched for +publisher:"Cornell University" +contributor:("Silcox, John"). Showing records 1 – 2 of 2 total matches.

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Cornell University

1. Hovden, Robert. Atomic Imaging With Highly Convergent Electron Beams .

Degree: 2014, Cornell University

Atoms and their arrangement in materials have become a central focus in the era of nanoscience. Materials and devices are now designed at the atomic level-exploiting unique quantum effects that manifest at confined scales. Observing the atomic world is often accomplished through the use of high-energy electrons. The recent advancement of aberration-corrected electromagnetic lenses have enabled highly convergent electron beams confined to lateral dimensions less than one angstrom. Local atomic structure can be probed by scattering sub-angstrom beams through a specimen, with atomic resolution images formed by measuring the scattered electrons as the beam is scanned. In this dissertation, we explore the imaging capabilities and limitations of highly convergent electron beams used in aberration-corrected scanning transmission electron microscopes (STEM). This work provides theoretical & computational approaches as well as experimental work on real systems-including semiconductor devices, nanoparticles used to catalyze hydrogen fuel cells, polymer scaffolds, and 2D membranes. The first two chapters provide a refreshed review of the imaging theory for elastically scattered electron beams. Chapter I motivates atomic characterization by high-energy electrons with their exceptional resolving power. Chapter II takes a more in-depth discussion of elastic scattering in STEM and how beam propagation can be described analytically and computationally. The limitations and detectability of single atoms are explored in Chapter III. The advent of clean monolayer membranes-like that of graphene-provide a playground for exploring the approaches to single atom imaging. Here, detection efficiency and interpretability of common detector geometries are optimized to improve signal-to-noise and open the possibility to single atom imaging of dose limited specimens. In Chapter IV, the thesis extends electron scattering to 3D crystals. When viewing a crystal down a principle zone axis, as is done to obtain atomic images, the complexity of the problem is reduced by mapping the propagating beam to the time evolution of a nonstationary state of a 2D-columnar "molecule". The excitation of the resulting 2D molecular orbitals have distinct characteristic signatures in the images that we are able to observe experimentally, and can drastically and predictably change the apparent location of atoms in samples currently used as resolution tests. Chapter V presents the problematic, small depth-of-field that accompanies highlyconvergent electron beams-causing regions in an extended object to appear blurred and poorly defined. This is overcome by implementing extended depth of field techniques that extract the in-focus regions from a through-focal image stack. Finally, in Chapter VI we discuss new possibilities for 3D imaging with highconvergence angles. To date, high-resolution (< 1 nm) imaging of extended objects in three-dimensions (3D) has not been possible. With current approaches, one is forced to choose between high resolution and large field of view.… Advisors/Committee Members: Silcox, John (committeeMember), Schlom, Darrell (committeeMember).

Subjects/Keywords: Electron Microscopy; Physics; Atomic Imaging

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Hovden, R. (2014). Atomic Imaging With Highly Convergent Electron Beams . (Thesis). Cornell University. Retrieved from http://hdl.handle.net/1813/36158

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Hovden, Robert. “Atomic Imaging With Highly Convergent Electron Beams .” 2014. Thesis, Cornell University. Accessed April 24, 2019. http://hdl.handle.net/1813/36158.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Hovden, Robert. “Atomic Imaging With Highly Convergent Electron Beams .” 2014. Web. 24 Apr 2019.

Vancouver:

Hovden R. Atomic Imaging With Highly Convergent Electron Beams . [Internet] [Thesis]. Cornell University; 2014. [cited 2019 Apr 24]. Available from: http://hdl.handle.net/1813/36158.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Hovden R. Atomic Imaging With Highly Convergent Electron Beams . [Thesis]. Cornell University; 2014. Available from: http://hdl.handle.net/1813/36158

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


Cornell University

2. Zhu, Pangshun. Signal Processing In Single Molecule Studies .

Degree: 2012, Cornell University

In this dissertation, I present signal processing techniques used in investigating single molecule kinetics and interactions. The first chapter provides an overview of signals and systems pertaining to single molecule studies. It discusses the need for signal processing, and gives a summary of current single molecule techniques. The second chapter introduces two techniques developed in our research using fluorescence microscopy, namely, spectral deconvolution in multi-color fluorescent microscopy systems; and fluorescent pattern recognition in the time domain using the correlation functions. In the third chapter, spectral deconvolution is demonstrated in separating autofluorescence from the fluorescence of enzyme label, used in quantitative fluorescence studies. In the fourth chapter, I discuss the fabrication of sub-wavelength metallic apertures that are used in single-molecule studies. I also discuss how optical properties of these devices are modeled and characterized. In the fifth chapter, I demonstrate how matched filter is used to give a precise quantitative measure of GFP fluorescence upon GFP aptamer binding. Similar technique is used to recognize photon bursts as a fluorescent molecule passes through an observation volume, discussed in the sixth chapter. I use this method to analyze the mobility of molecules in a fluidic channel. Chapter seven provides a summary and outlook for future studies. Advisors/Committee Members: Hass, Jerome E. (committeeMember), Lis, John T (committeeMember), Silcox, John (committeeMember).

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Zhu, P. (2012). Signal Processing In Single Molecule Studies . (Thesis). Cornell University. Retrieved from http://hdl.handle.net/1813/29457

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Zhu, Pangshun. “Signal Processing In Single Molecule Studies .” 2012. Thesis, Cornell University. Accessed April 24, 2019. http://hdl.handle.net/1813/29457.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Zhu, Pangshun. “Signal Processing In Single Molecule Studies .” 2012. Web. 24 Apr 2019.

Vancouver:

Zhu P. Signal Processing In Single Molecule Studies . [Internet] [Thesis]. Cornell University; 2012. [cited 2019 Apr 24]. Available from: http://hdl.handle.net/1813/29457.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Zhu P. Signal Processing In Single Molecule Studies . [Thesis]. Cornell University; 2012. Available from: http://hdl.handle.net/1813/29457

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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