Fig. 2
From: A molecular overlayer with the Fibonacci square grid structure
Fast Fourier transform and autocorrelation function. a Fast Fourier transform (FFT) of a scanning tunnelling microscopy (STM) image of the clean surface, demonstrating two-fold symmetry. b FFT of the C60 molecules of Fig. 1c. c FFT generated from a Fibonacci square grid, showing four-fold symmetry. Spots of the first two orders of diffraction are highlighted by circles of different colours. FFTs in a, b are displayed with the same k-vector scale, while the scale of c is arbitrary. d Autocorrelation function of the STM image of the C60 overlayer of Fig. 1c. A distorted square is marked. e Autocorrelation function taken from point objects at the vertices of a Fibonacci square grid of S = 1.26 nm, L = 2.04 nm. Scale bars in d, e represent 1 nm
