title: Subwavelength imaging through ion-beam-induced upconversion.
abstract: The combination of an optical microscope and a luminescent probe plays a pivotal role in biological imaging because it allows for probing subcellular structures. However, the optical resolutions are largely constrained by Abbe's diffraction limit, and the common dye probes often suffer from photobleaching. Here we present a new method for subwavelength imaging by combining lanthanide-doped upconversion nanocrystals with the ionoluminescence imaging technique. We experimentally observed that the ion beam can be used as a new form of excitation source to induce photon upconversion in lanthanide-doped nanocrystals. This approach enables luminescence imaging and simultaneous mapping of cellular structures with a spatial resolution of sub-30 nm.
authors.affiliation: Department of Physics, Centre for Ion Beam Applications, National University of Singapore, Singapore 117542, Singapore.
authors.forename: Zhaohong
authors.identifier: http://orcid.org/0000-0002-9838-3382
authors.initials: Z
authors.lastname: Mi
authors.affiliation: Department of Chemistry, National University of Singapore, Singapore 117543, Singapore.
authors.forename: Yuhai
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Physics, Centre for Ion Beam Applications, National University of Singapore, Singapore 117542, Singapore.
authors.forename: Sudheer Kumar
authors.identifier: http://orcid.org/0000-0002-3192-0526
authors.initials: SK
authors.lastname: Vanga
authors.affiliation: Department of Physics, Centre for Ion Beam Applications, National University of Singapore, Singapore 117542, Singapore.
authors.forename: Ce-Belle
authors.initials: CB
authors.lastname: Chen
authors.affiliation: Department of Physics, Centre for Ion Beam Applications, National University of Singapore, Singapore 117542, Singapore.
authors.forename: Hong Qi
authors.initials: HQ
authors.lastname: Tan
authors.affiliation: Department of Physics, Centre for Ion Beam Applications, National University of Singapore, Singapore 117542, Singapore.
authors.forename: Frank
authors.initials: F
authors.lastname: Watt
authors.affiliation: Department of Chemistry, National University of Singapore, Singapore 117543, Singapore.|Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Singapore 117602, Singapore.|Center for Functional Materials, NUS (Suzhou) Research Institute, Suzhou, Jiangsu 215123, China.
authors.forename: Xiaogang
authors.identifier: http://orcid.org/0000-0003-2517-5790
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Physics, Centre for Ion Beam Applications, National University of Singapore, Singapore 117542, Singapore.|Yale-NUS College, Singapore 138527, Singapore.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Bettiol