Fig. 3

a–d Experiment versus simulation frequency power spectrum based on wavelet transform. (x-1)–(x-4) are experimental results, and L = 58, 116, and 216 indicate three single scan lines to be calculated in (x-1), respectively. (x-5) are simulation results. δ_s and δ_c denote the ratio from the simulation and calculation (Eq. 2), respectively. (x-1) are “atomic resolution” AFM lateral force images with real lattice structures (black mesh)