Fig. 3
STM images and nc-AFM frequency shift maps of the H-type product 4. a, b Overview and high-resolution STM images of the sample after annealing to 420 K, recorded at 93 K. The axes of molecular backbones are marked by black lines. c LT-STM image of H-type product 4 by using a Br-tip, recorded at 4.3 K. d Zoom-in LT-STM image of the molecule circled in c. The formed phenyl is pointed by the white arrow. e, f STM image and the corresponding nc-AFM frequency shift map of a same area composed by H-type product 4, by using a Br-tip. One of the ethynylenes of 4 in nc-AFM frequency shift map is pointed by the yellow arrow. Tunneling parameters: a V = −2 V, I = −0.2 nA; b V = −0.2 V, I = −0.6 nA; c, d V = 0.1 V, I = 1.0 nA; e V = 1 V, I = 0.2 nA; f V = 0 V, Δf: −9.8 to −4.8 Hz. Color code: C, gray; H, white
