Fig. 2: PiFM imaging on one nanoellipsoid of a ZAIS QD.
a AFM image of the ZAIS QD. b, c PiFM images of the ZAIS QD at 660 and 785 nm, respectively. d Δf(fm)X at 660 nm, and the profile of Δz in the middle of the ZAIS QD. This plot indicates that a spatial imaging resolution of ~0.7 nm was achieved. The positions at which the profiles were acquired are indicated in the insets. During imaging, the tip–sample distance was controlled via feedback control (Δf = − 20 Hz) with A = 10 nm.
