Kirkland, WA, United States
Kirkland, WA, United States
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Dwyer C.,Arizona State University | Aoki T.,Arizona State University | Rez P.,Arizona State University | Chang S.L.Y.,Arizona State University | And 3 more authors.
Physical Review Letters | Year: 2016

We demonstrate that a focused beam of high-energy electrons can be used to map the vibrational modes of a material with a spatial resolution of the order of one nanometer. Our demonstration is performed on boron nitride, a polar dielectric which gives rise to both localized and delocalized electron-vibrational scattering, either of which can be selected in our off-axial experimental geometry. Our experimental results are well supported by our calculations, and should reconcile current controversy regarding the spatial resolution achievable in vibrational mapping with focused electron beams. © 2016 American Physical Society.


Krivanek O.L.,Nion Company | Chisholm M.F.,Oak Ridge National Laboratory | Murfitt M.F.,Nion Company | Dellby N.,Nion Company
Ultramicroscopy | Year: 2012

Some four decades were needed to catch up with the vision that Albert Crewe and his group had for the scanning transmission electron microscope (STEM) in the nineteen sixties and seventies: attaining 0.5. Å resolution, and identifying single atoms spectroscopically. With these goals now attained, STEM developments are turning toward new directions, such as rapid atomic resolution imaging and exploring atomic bonding and electronic properties of samples at atomic resolution. The accomplishments and the future challenges are reviewed and illustrated with practical examples. © 2012 Elsevier B.V.


Brown L.M.,University of Cambridge | Batson P.E.,Rutgers University | Dellby N.,Nion Company | Krivanek O.L.,Nion Company | Krivanek O.L.,Arizona State University
Ultramicroscopy | Year: 2015

We provide a brief history of the project to correct the spherical aberration of the scanning transmission electron microscope (STEM) that started in Cambridge (UK) and continued in Kirkland (WA, USA), Yorktown Heights (NY, USA), and other places. We describe the project in the full context of other aberration correction research and related work, partly in response to the incomplete context presented in the paper "In quest of perfection in electron optics: A biographical sketch of Harald Rose on the occasion of his 80th birthday", recently published in Ultramicroscopy. © 2015 Elsevier B.V.


Shu G.,University of Washington | Shu G.,Georgia Institute of Technology | Chou C.-K.,University of Washington | Kurz N.,University of Washington | And 4 more authors.
Journal of the Optical Society of America B: Optical Physics | Year: 2011

Trapped, laser-cooled atoms and ions produce intense fluorescence of the order 107 ~ 108 photons per second. Detection of this fluorescence enables efficient measurement of the quantum state of qubits based on trapped atoms. It is desirable to collect a large fraction of the photons to make the detection faster and more reliable. Additionally, efficient fluorescence collection can improve the speed and fidelity of remote ion entanglement and quantum gates. Refractive and reflective optics, and optical cavities have all been used to collect the trapped ion fluorescence with up to about 10% efficiency. Here we show a novel ion trap design that incorporates a metallic spherical mirror as the integral part of the trap itself, being its RF electrode. The mirror geometry enables up to 35% solid angle collection of trapped ion fluorescence. The movable central pin electrode of this trap allows precise placement of the ion at the focus of the reflector. We characterize the performance of the mirror, and measure 25% collection efficiency, likely limited by the imperfections of the mirror surface. We also study the properties of the images of single ions formed by the spherical mirror and apply aberration correction with an aspherical element placed outside the vacuum system. Owing to the simplicity of its design, this trap structure can be adapted for microfabrication and integration into more complex trap architectures. © 2011 Optical Society of America.


Krivanek O.L.,Nion Company | Krivanek O.L.,Arizona State University | Lovejoy T.C.,Nion Company | Dellby N.,Nion Company | Carpenter R.W.,Arizona State University
Journal of Electron Microscopy | Year: 2013

The origins and the recent accomplishments of aberration correction in scanning transmission electron microscopy (STEM) are reviewed. It is remembered that the successful correction of imaging aberrations of round lenses owes much to the successful correction of spectrum aberrations achieved in electron energy loss spectrometers 2-3 decades earlier. Two noteworthy examples of the types of STEM investigation that aberration correction has made possible are shown: imaging of single-atom impurities in graphene and analyzing atomic bonding of single atoms by electron energy loss spectroscopy (EELS). Looking towards the future, a new all-magnetic monochromator is described. The monochromator uses several of the principles pioneered in round lens aberration correction, and it employs stabilization schemes that make it immune to variations in the high voltage of the microscope and in the monochromator main prism current. Tests of the monochromator carried out at 60 keV have demonstrated energy resolution as good as 12 meV and monochromated probe size of ∼1.2 Å. These results were obtained in separate experiments, but they indicate that the instrument can perform imaging and EELS with an atom-sized probe <30 meV wide in energy, and that an improvement in energy resolution to 10 meV and beyond should be possible in the future. © The Author 2013. Published by Oxford University Press [on behalf of The Japanese Society of Microscopy]. All rights reserved.


Grant
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 994.30K | Year: 2013

If the energy resolution of electron energy loss spectroscopy (EELS) carried out in a scanning transmission electron microscope (STEM), with an atom-sized electron probe, could be improved to 10 meV or better, a new way of studying materials at the atomic scale, by recording and analyzing their vibrational energies, would become possible. No STEM system capable of such performance has yet been developed. Up to a few months ago, the best energy resolution that could be obtained with monochromated EELS systems capable of forming a small probe was about 40 meV, i.e. a factor of 4 too poor. Using a new monochromator we have recently built and an improved Gatan spectrometer, we have shown that resolution of 10 meV and eventually 5 meV will become possible, if the spectrometer part of our new instrument is brought up to the same design standards as the new monochromator. Building such a spectrometer is what we plan to do in the proposed project. In Phase I we built and brought up a monochromated STEM that uses a new type of a Nion- designed monochromator, and achieved unprecedented levels of performance. The spectrometer used in this project was Gatans latest design, the Enfinium, with two enhancements for extra stability. The system was able to reach 12 meV energy resolution in spectra taken with very short acquisition times, but not in spectra taken with acquisition times of around 1 s. Pushing the whole system to reach unprecedented levels of energy resolution has taught us what is and what is not important in ultra-high resolution EELS. We used this knowledge to design a new spectrometer with improved electron optics, and detectors optimized for detecting weak spectral features next to an intense zero loss peak. The newly designed spectrometer will be built, in two stages during Phase II. Stage A spectrometer will be built in the first year. It will reach 10 meV energy resolution at 60 keV, and it will provide a test bed for key design elements of stage B. The Stage B spectrometer, which will be mostly built in the first year and brought up and optimized in the second year, will be designed to reach 5 meV energy resolution. Commercial Applications and Other Benefits: Elements as light as hydrogen will become detectable, and their bonding arrangements determined from the observed vibrational energies. This will increase our understanding of energy conversion and storage devices needed for a green economy. The new spectrometer and the associated equipment (a complete monochromated scanning transmission electron microscope) will open up a new market segment in research instrumentation, which we estimate will be worth about $20M per year for Nion.


Grant
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 134.12K | Year: 2012

If the energy resolution of electron energy loss spectroscopy carried out in an electron microscope, with an atom-sized electron probe, could be improved to 10 meV or better, a new way of studying materials at the atomic scale, by recording and analyzing their vibrational energies, would become possible. The energy resolution attainable with present-day monochromated electron microscopes and spectrometers is about ten times too poor for such studies. Nion Company is now building a monochromator that will achieve the required performance. This proposal requests funds for designing and building a spectrometer able to record electron energy loss spectra with a matching energy resolution. We will design and build and all-magnetic Ultra-High Energy Resolution Electron Spectrometer(UHERES) that will deliver an energy resolution of ~10 meV at 100 keV primary and ~5 meV at 40 keV. The spectrometer will work together with the new monochromator and the Nion UltraSTEM electron microscope, which will illuminate the sample with an atom-sized electron beam. Commercial applications and other benefits: Determining the energies of vibrational modes experimentally will open a fundamentally new window on the study of atomic arrangements at interfaces, grain boundaries, point defects and surfaces. Elements as light as hydrogen are likely to become detectable, and their bonding arrangements easily determined from the observed vibrational energies. Being able to determine the positions and bonding of light atoms is especially important for understanding and designing energy conversion and storage devices needed for a green economy. The new spectrometer and the associated equipment (a complete monochromated scanning transmission electron microscope) will open up a new market segment in research instrumentation, which we estimate will be worth about $20M per year for Nion.


PubMed | Arizona State University and Nion Company
Type: Journal Article | Journal: Physical review letters | Year: 2016

We demonstrate that a focused beam of high-energy electrons can be used to map the vibrational modes of a material with a spatial resolution of the order of one nanometer. Our demonstration is performed on boron nitride, a polar dielectric which gives rise to both localized and delocalized electron-vibrational scattering, either of which can be selected in our off-axial experimental geometry. Our experimental results are well supported by our calculations, and should reconcile current controversy regarding the spatial resolution achievable in vibrational mapping with focused electron beams.


PubMed | Arizona State University, Rutgers University, University of Cambridge and Nion Company
Type: | Journal: Ultramicroscopy | Year: 2015

We provide a brief history of the project to correct the spherical aberration of the scanning transmission electron microscope (STEM) that started in Cambridge (UK) and continued in Kirkland (WA, USA), Yorktown Heights (NY, USA), and other places. We describe the project in the full context of other aberration correction research and related work, partly in response to the incomplete context presented in the paper In quest of perfection in electron optics: A biographical sketch of Harald Rose on the occasion of his 80th birthday, recently published in Ultramicroscopy.


PubMed | University of Alberta, Arizona State University, Rutgers University and Nion Company
Type: Journal Article | Journal: Nature | Year: 2014

Vibrational spectroscopies using infrared radiation, Raman scattering, neutrons, low-energy electrons and inelastic electron tunnelling are powerful techniques that can analyse bonding arrangements, identify chemical compounds and probe many other important properties of materials. The spatial resolution of these spectroscopies is typically one micrometre or more, although it can reach a few tens of nanometres or even a few ngstrms when enhanced by the presence of a sharp metallic tip. If vibrational spectroscopy could be combined with the spatial resolution and flexibility of the transmission electron microscope, it would open up the study of vibrational modes in many different types of nanostructures. Unfortunately, the energy resolution of electron energy loss spectroscopy performed in the electron microscope has until now been too poor to allow such a combination. Recent developments that have improved the attainable energy resolution of electron energy loss spectroscopy in a scanning transmission electron microscope to around ten millielectronvolts now allow vibrational spectroscopy to be carried out in the electron microscope. Here we describe the innovations responsible for the progress, and present examples of applications in inorganic and organic materials, including the detection of hydrogen. We also demonstrate that the vibrational signal has both high- and low-spatial-resolution components, that the first component can be used to map vibrational features at nanometre-level resolution, and that the second component can be used for analysis carried out with the beam positioned just outside the sample--that is, for aloof spectroscopy that largely avoids radiation damage.

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