Formation of Se- 3 monolayer on Au(111) at 250 °C. [(a), (b), (d)] Large-scale and atomic-resolution [(b), (d)] STM images of Se- 3 monolayer. The inset in panel (a) is the corresponding FFT image. (c) FFT image of the atomic-resolution STM image of Se- 3 monolayer with a scanning area of 25 nm × 25 nm. (e) Series of d I/d V spectra taken along the line indicated in panel (b). Tunneling conditions: (a) V_bias = –2.0 V, I_set = 200 pA; (b) V_bias = 1.0 V, I_set = 500 PA; (d) V_bias = 1.5 V, I_set = 500 pA; (e) V_bias = –2.0 V, I_set = 500 pA.