fig2

Figure 2. (A) Atomic resolution STM image of Sn-I phase with the unit cell marked by the rhombus (-50 mV, 50 pA). (B) Fast Fourier transform (FFT) image of (A) with the periodicity of 2√7a × 2√7a structure, 2√7/3a × 2√7/3a structure, and the dodecagonal periodicity (12-fold) marked by light blue, purple, and green circles. (C and D) Inverse-FFT image obtained from the 2√7a × 2√7a structure and the dodecagonal periodicity marked by light blue and green circles in (B), respectively. (E) Sketch of the 2√7a × 2√7a structure on the Al(111) substrate. (F) Sketch of the triangle-square-pentagon tiling on the surface of Sn-I phase, with the unit cell of 2√7a × 2√7a marked by the light blue rhombus and the dodecagonal periodicity marked by green shapes, respectively.