Fig. 1: Ionoluminescence nanoscopy.

a Schematic illustration of the basic beam optics and experimental setup. Note that ionoluminescent photons emitted from the nanodiamonds induced by the α-beam are collected with a parabolic-mirror-based system and detected with a photomultiplier tube for ionoluminescence mapping (see Supplementary Fig. 3). b Nitrogen-vacancy (NV) center in the diamond crystalline structure. c Ionoluminescence image of the nanodiamonds through α-particle excitation. Scale bar, 2 μm. d Confocal image of the same region of the nanodiamond sample taken by using 543-nm laser excitation. Scale bar, 2 μm. e Cross-sectional line profile extracted along the arrow shown in the inset of a high-magnification image that corresponds to the region of interest marked in c, demonstrating the discrimination of two single nanodiamonds with a size of 38 and 35 nm, respectively. f Cross-sectional line profile extracted along the arrow depicted in the inset of a high-magnification image that hosts two single nanodiamonds with a separation distance approximating the resolving limit, directly indicating a sub-40 nm resolution of the ionoluminescence image.