[{"publication_status":"published","abstract":[{"text":"We present a novel design for an ultracompact, passive light source capable of generating ultraviolet and X-ray radiation, based on the interaction of free electrons with the magnetic near-field of a ferromagnet. Our design is motivated by recent advances in the fabrication of nanostructures, which allow the confinement of large magnetic fields at the surface of ferromagnetic nanogratings. Using ab initio simulations and a complementary analytical theory, we show that highly directional, tunable, monochromatic radiation at high frequencies could be produced from relatively low-energy electrons within a tabletop design. The output frequency is tunable in the extreme ultraviolet to hard X-ray range via electron kinetic energies from 1 keV to 5 MeV and nanograting periods from 1 μm to 5 nm. The proposed radiation source can achieve the tunability and monochromaticity of current free-electron-driven sources (free-electron lasers, synchrotrons, and laser-driven undulators), yet with a significantly reduced scale, cost, and complexity. Our design could help realize the next generation of tabletop or on-chip X-ray sources.","lang":"eng"}],"status":"public","day":"01","extern":"1","publication":"ACS Photonics","citation":{"ama":"Fisher S, Roques-Carmes C, Rivera N, Wong LJ, Kaminer I, Soljačić M. Monochromatic X-ray source based on scattering from a magnetic nanoundulator. <i>ACS Photonics</i>. 2020;7(5):1096-1103. doi:<a href=\"https://doi.org/10.1021/acsphotonics.0c00121\">10.1021/acsphotonics.0c00121</a>","short":"S. Fisher, C. Roques-Carmes, N. Rivera, L.J. Wong, I. Kaminer, M. Soljačić, ACS Photonics 7 (2020) 1096–1103.","ieee":"S. Fisher, C. Roques-Carmes, N. Rivera, L. J. Wong, I. Kaminer, and M. Soljačić, “Monochromatic X-ray source based on scattering from a magnetic nanoundulator,” <i>ACS Photonics</i>, vol. 7, no. 5. American Chemical Society , pp. 1096–1103, 2020.","ista":"Fisher S, Roques-Carmes C, Rivera N, Wong LJ, Kaminer I, Soljačić M. 2020. Monochromatic X-ray source based on scattering from a magnetic nanoundulator. ACS Photonics. 7(5), 1096–1103.","chicago":"Fisher, Sophie, Charles Roques-Carmes, Nicholas Rivera, Liang Jie Wong, Ido Kaminer, and Marin Soljačić. “Monochromatic X-Ray Source Based on Scattering from a Magnetic Nanoundulator.” <i>ACS Photonics</i>. American Chemical Society , 2020. <a href=\"https://doi.org/10.1021/acsphotonics.0c00121\">https://doi.org/10.1021/acsphotonics.0c00121</a>.","apa":"Fisher, S., Roques-Carmes, C., Rivera, N., Wong, L. J., Kaminer, I., &#38; Soljačić, M. (2020). Monochromatic X-ray source based on scattering from a magnetic nanoundulator. <i>ACS Photonics</i>. American Chemical Society . <a href=\"https://doi.org/10.1021/acsphotonics.0c00121\">https://doi.org/10.1021/acsphotonics.0c00121</a>","mla":"Fisher, Sophie, et al. “Monochromatic X-Ray Source Based on Scattering from a Magnetic Nanoundulator.” <i>ACS Photonics</i>, vol. 7, no. 5, American Chemical Society , 2020, pp. 1096–103, doi:<a href=\"https://doi.org/10.1021/acsphotonics.0c00121\">10.1021/acsphotonics.0c00121</a>."},"publisher":"American Chemical Society ","_id":"21525","article_type":"letter_note","date_updated":"2026-04-15T11:51:29Z","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","OA_place":"publisher","date_created":"2026-03-30T12:22:47Z","ddc":["530"],"OA_type":"hybrid","pmid":1,"scopus_import":"1","date_published":"2020-04-01T00:00:00Z","doi":"10.1021/acsphotonics.0c00121","oa_version":"Published Version","year":"2020","month":"04","title":"Monochromatic X-ray source based on scattering from a magnetic nanoundulator","main_file_link":[{"open_access":"1","url":"https://doi.org/10.1021/acsphotonics.0c00121"}],"issue":"5","article_processing_charge":"No","quality_controlled":"1","type":"journal_article","author":[{"last_name":"Fisher","first_name":"Sophie","full_name":"Fisher, Sophie"},{"full_name":"Roques-Carmes, Charles","first_name":"Charles","id":"e2e68fc9-6505-11ef-a541-eb4e72cc3e82","last_name":"Roques-Carmes"},{"last_name":"Rivera","first_name":"Nicholas","full_name":"Rivera, Nicholas"},{"last_name":"Wong","first_name":"Liang Jie","full_name":"Wong, Liang Jie"},{"first_name":"Ido","last_name":"Kaminer","full_name":"Kaminer, Ido"},{"full_name":"Soljačić, Marin","first_name":"Marin","last_name":"Soljačić"}],"keyword":["X-ray sources","free electrons","nanostructure","undulator","synchrotron","free-electron laser"],"has_accepted_license":"1","volume":7,"language":[{"iso":"eng"}],"page":"1096-1103","tmp":{"name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)","image":"/images/cc_by.png","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"oa":1,"external_id":{"pmid":[" 32596415"],"arxiv":["1910.09629"]},"arxiv":1,"publication_identifier":{"eissn":["2330-4022"]},"intvolume":"         7"},{"issue":"43","title":"Fe3O4@NiFexOy nanoparticles with enhanced electrocatalytic properties for oxygen evolution in carbonate electrolyte","month":"11","year":"2016","oa_version":"None","doi":"10.1021/acsami.6b09888","scopus_import":"1","date_published":"2016-11-02T00:00:00Z","publication_identifier":{"eissn":["1944-8252"],"issn":["1944-8244"]},"intvolume":"         8","external_id":{"pmid":["27730808"]},"language":[{"iso":"eng"}],"page":"29461 - 29469","keyword":["nanoparticle","iron oxide","magnetite","core−shell nanostructure","electrocatalysts","oxygen evolution reaction","OER"],"volume":8,"author":[{"first_name":"Zhishan","last_name":"Luo","full_name":"Luo, Zhishan"},{"first_name":"Sara","last_name":"Márti Sánchez","full_name":"Márti Sánchez, Sara"},{"full_name":"Nafria, Raquel","last_name":"Nafria","first_name":"Raquel"},{"full_name":"Joshua, Gihan","first_name":"Gihan","last_name":"Joshua"},{"full_name":"De La Mata, Maria","last_name":"De La Mata","first_name":"Maria"},{"first_name":"Pablo","last_name":"Guardia","full_name":"Guardia, Pablo"},{"full_name":"Flox, Christina","last_name":"Flox","first_name":"Christina"},{"last_name":"Martínez Boubeta","first_name":"Carlos","full_name":"Martínez Boubeta, Carlos"},{"full_name":"Simeonidis, Konstantinos","first_name":"Konstantinos","last_name":"Simeonidis"},{"full_name":"Llorca, Jordi","first_name":"Jordi","last_name":"Llorca"},{"last_name":"Morante","first_name":"Joan","full_name":"Morante, Joan"},{"full_name":"Arbiol, Jordi","last_name":"Arbiol","first_name":"Jordi"},{"full_name":"Ibanez Sabate, Maria","orcid":"0000-0001-5013-2843","first_name":"Maria","id":"43C61214-F248-11E8-B48F-1D18A9856A87","last_name":"Ibanez Sabate"},{"full_name":"Cabot, Andreu","first_name":"Andreu","last_name":"Cabot"}],"article_processing_charge":"No","quality_controlled":"1","type":"journal_article","publist_id":"7458","day":"02","abstract":[{"lang":"eng","text":"The design and engineering of earth-abundant catalysts that are both cost-effective and highly active for water splitting are crucial challenges in a number of energy conversion and storage technologies. In this direction, herein we report the synthesis of Fe3O4@NiFexOy core-shell nanoheterostructures and the characterization of their electrocatalytic performance toward the oxygen evolution reaction (OER). Such nanoparticles (NPs) were produced by a two-step synthesis procedure involving the colloidal synthesis of Fe3O4 nanocubes with a defective shell and the posterior diffusion of nickel cations within this defective shell. Fe3O4@NiFexOy NPs were subsequently spin-coated over ITO-covered glass and their electrocatalytic activity toward water oxidation in carbonate electrolyte was characterized. Fe3O4@NiFexOy catalysts reached current densities above 1 mA/cm2 with a 410 mV overpotential and Tafel slopes of 48 mV/dec, which is among the best electrocatalytic performances reported in carbonate electrolyte."}],"status":"public","publication_status":"published","pmid":1,"acknowledgement":"This work was supported by the European Regional Development Funds and the Spanish MINECO project BOOSTER, TNT-FUELS, e-TNT, Severo Ochoa Program (MINECO, Grant SEV-2013-0295), and PEC?CO2. Z.L. thanks the China Scholarship Council for scholarship support. P.G. acknowledges the People Programme (Marie Curie Actions) of the FP7/2007-2013 European Union Program (TECNIOspring grant agreement no. 600388) and the Agency for Business Competitiveness of the Government of Catalonia, ACCIO. M.I. thanks AGAUR for Beatriu de Pinos postdoctoral grant (2013 BP-A00344).\r\n\r\n","OA_type":"closed access","date_created":"2018-12-11T11:46:05Z","user_id":"ba8df636-2132-11f1-aed0-ed93e2281fdd","publisher":"American Chemical Society","citation":{"short":"Z. Luo, S. Márti Sánchez, R. Nafria, G. Joshua, M. De La Mata, P. Guardia, C. Flox, C. Martínez Boubeta, K. Simeonidis, J. Llorca, J. Morante, J. Arbiol, M. Ibáñez, A. Cabot, Applied Materials and Interfaces 8 (2016) 29461–29469.","ieee":"Z. Luo <i>et al.</i>, “Fe3O4@NiFexOy nanoparticles with enhanced electrocatalytic properties for oxygen evolution in carbonate electrolyte,” <i>Applied Materials and Interfaces</i>, vol. 8, no. 43. American Chemical Society, pp. 29461–29469, 2016.","ama":"Luo Z, Márti Sánchez S, Nafria R, et al. Fe3O4@NiFexOy nanoparticles with enhanced electrocatalytic properties for oxygen evolution in carbonate electrolyte. <i>Applied Materials and Interfaces</i>. 2016;8(43):29461-29469. doi:<a href=\"https://doi.org/10.1021/acsami.6b09888\">10.1021/acsami.6b09888</a>","ista":"Luo Z, Márti Sánchez S, Nafria R, Joshua G, De La Mata M, Guardia P, Flox C, Martínez Boubeta C, Simeonidis K, Llorca J, Morante J, Arbiol J, Ibáñez M, Cabot A. 2016. Fe3O4@NiFexOy nanoparticles with enhanced electrocatalytic properties for oxygen evolution in carbonate electrolyte. Applied Materials and Interfaces. 8(43), 29461–29469.","chicago":"Luo, Zhishan, Sara Márti Sánchez, Raquel Nafria, Gihan Joshua, Maria De La Mata, Pablo Guardia, Christina Flox, et al. “Fe3O4@NiFexOy Nanoparticles with Enhanced Electrocatalytic Properties for Oxygen Evolution in Carbonate Electrolyte.” <i>Applied Materials and Interfaces</i>. American Chemical Society, 2016. <a href=\"https://doi.org/10.1021/acsami.6b09888\">https://doi.org/10.1021/acsami.6b09888</a>.","mla":"Luo, Zhishan, et al. “Fe3O4@NiFexOy Nanoparticles with Enhanced Electrocatalytic Properties for Oxygen Evolution in Carbonate Electrolyte.” <i>Applied Materials and Interfaces</i>, vol. 8, no. 43, American Chemical Society, 2016, pp. 29461–69, doi:<a href=\"https://doi.org/10.1021/acsami.6b09888\">10.1021/acsami.6b09888</a>.","apa":"Luo, Z., Márti Sánchez, S., Nafria, R., Joshua, G., De La Mata, M., Guardia, P., … Cabot, A. (2016). Fe3O4@NiFexOy nanoparticles with enhanced electrocatalytic properties for oxygen evolution in carbonate electrolyte. <i>Applied Materials and Interfaces</i>. American Chemical Society. <a href=\"https://doi.org/10.1021/acsami.6b09888\">https://doi.org/10.1021/acsami.6b09888</a>"},"publication":"Applied Materials and Interfaces","date_updated":"2026-05-13T13:32:06Z","_id":"371","article_type":"original","extern":"1"}]