Honors & Awards

  • Maria Goeppert Mayer Fellow, Argonne National Laboratory (2021-2024)
  • National Defense Science and Engineering Graduate Fellow, U.S. Department of Defense (2017-2021)
  • Ryan Fellow, International Institute for Nanotechnology, Northwestern University (2017-2020)

Professional Education

  • Doctor of Philosophy, Northwestern University (2021)
  • Ph.D., Northwestern University, Applied Physics (2021)
  • B.A., University of California, Berkeley, Physics (2012)

Stanford Advisors

All Publications

  • Concurrent multi-peak Bragg coherent x-ray diffraction imaging of 3D nanocrystal lattice displacement via global optimization NPJ COMPUTATIONAL MATERIALS Maddali, S., Frazer, T. D., Delegan, N., Harmon, K. J., Sullivan, S. E., Allain, M., Cha, W., Dibos, A., Poudyal, I., Kandel, S., Nashed, Y. G., Heremans, F., You, H., Cao, Y., Hruszkewycz, S. O. 2023; 9 (1)
  • Designing silicon carbide heterostructures for quantum information science: challenges and opportunities MATERIALS FOR QUANTUM TECHNOLOGY Harmon, K. J., Delegan, N., Highland, M. J., He, H., Zapol, P., Heremans, F. J., Hruszkewycz, S. O. 2022; 2 (2)
  • Nonreciprocal interactions induced by water in confinement PHYSICAL REVIEW RESEARCH Jimenez-Angeles, F., Harmon, K. J., Trung Dac Nguyen, Fenter, P., de la Cruz, M. 2020; 2 (4)
  • Validating first-principles molecular dynamics calculations of oxide/water interfaces with x-ray reflectivity data PHYSICAL REVIEW MATERIALS Harmon, K. J., Letchworth-Weaver, K., Gaiduk, A. P., Giberti, F., Gygi, F., Chan, M. Y., Fenter, P., Galli, G. 2020; 4 (11)
  • Insights on the Alumina Water Interface Structure by Direct Comparison of Density Functional Simulations with X-ray Reflectivity JOURNAL OF PHYSICAL CHEMISTRY C Harmon, K. J., Chen, Y., Bylaska, E. J., Catalano, J. G., Bedzyk, M. J., Weare, J. H., Fenter, P. 2018; 122 (47): 26934-26944
  • Enhancing Tabletop X-Ray Phase Contrast Imaging with Nano-Fabrication. Scientific reports Miao, H., Gomella, A. A., Harmon, K. J., Bennett, E. E., Chedid, N., Znati, S., Panna, A., Foster, B. A., Bhandarkar, P., Wen, H. 2015; 5: 13581


    X-ray phase-contrast imaging is a promising approach for improving soft-tissue contrast and lowering radiation dose in biomedical applications. While current tabletop imaging systems adapt to common x-ray tubes and large-area detectors by employing absorptive elements such as absorption gratings or monolithic crystals to filter the beam, we developed nanometric phase gratings which enable tabletop x-ray far-field interferometry with only phase-shifting elements, leading to a substantial enhancement in the performance of phase contrast imaging. In a general sense the method transfers the demands on the spatial coherence of the x-ray source and the detector resolution to the feature size of x-ray phase masks. We demonstrate its capabilities in hard x-ray imaging experiments at a fraction of clinical dose levels and present comparisons with the existing Talbot-Lau interferometer and with conventional digital radiography.

    View details for DOI 10.1038/srep13581

    View details for PubMedID 26315891

    View details for PubMedCentralID PMC4551996

  • Motionless electromagnetic phase stepping versus mechanical phase stepping in x-ray phase-contrast imaging with a compact source. Physics in medicine and biology Harmon, K. J., Miao, H., Gomella, A. A., Bennett, E. E., Foster, B. A., Bhandarkar, P., Wen, H. 2015; 60 (8): 3031-43


    X-ray phase contrast imaging based on grating interferometers detects the refractive index distribution of an object without relying on radiation attenuation, thereby having the potential for reduced radiation absorption. These techniques belong to the broader category of optical wavefront measurement, which requires stepping the phase of the interference pattern to obtain a pixel-wise map of the phase distortion of the wavefront. While phase stepping traditionally involves mechanical scanning of a grating or mirror, we developed electromagnetic phase stepping (EPS) for imaging with compact sources to obviate the need for mechanical movement. In EPS a solenoid coil is placed outside the x-ray tube to shift its focal spot with a magnetic field, causing a relative movement between the projection of the sample and the interference pattern in the image. Here we present two embodiments of this method. We verified experimentally that electromagnetic and mechanical phase stepping give the same results and attain the same signal-to-noise ratios under the same radiation dose. We found that the relative changes of interference fringe visibility were within 3.0% when the x-ray focal spot was shifted by up to 1.0 mm in either direction. We conclude that when using x-ray tube sources, EPS is an effective means of phase stepping without the need for mechanical movement.

    View details for DOI 10.1088/0031-9155/60/8/3031

    View details for PubMedID 25803511

    View details for PubMedCentralID PMC6933752

  • Efficient decoding of 2D structured illumination with linear phase stepping in X-ray phase contrast and dark-field imaging. PloS one Harmon, K. J., Bennett, E. E., Gomella, A. A., Wen, H. 2014; 9 (1): e87127


    The ability to map the phase distribution and lateral coherence of an x-ray wavefront offers the potential for imaging the human body through phase contrast, without the need to deposit significant radiation energy. The classic means to achieve this goal is structured illumination, in which a periodic intensity modulation is introduced into the image, and changes in the phase distribution of the wavefront are detected as distortions of the modulation pattern. Two-dimensional periodic patterns are needed to fully characterize a transverse wavefront. Traditionally, the information in a 2D pattern is retrieved at high resolution by acquiring multiple images while shifting the pattern over a 2D matrix of positions. Here we describe a method to decode 2D periodic patterns with single-axis phase stepping, without either a loss of information or increasing the number of sampling steps. The method is created to reduce the instrumentation complexity of high-resolution 2D wavefront sensing in general. It is demonstrated with motionless electromagnetic phase stepping and a flexible processing algorithm in x-ray dark-field and phase contrast imaging.

    View details for DOI 10.1371/journal.pone.0087127

    View details for PubMedID 24489853

    View details for PubMedCentralID PMC3904978