Figure 6

(Color) A sequence of STM images of hematite (001) taken in-situ in pH 1 HNO₃ at room temperature using insulated tips. Bias voltages, image size (e.g., 15 nm = 15 × 15 nm image) and acquisition time are given in the figure. All images are height images with a vertical color scale of 0.3 nm. Nonperiodic sites are observed mostly at higher negative bias and earlier in the experiment. After over 2 h from the start of the experiment, non-periodic surface sites are less common, particularly those that protrude more than 0.23 nm, even at higher negative bias voltage [(g)–(i)].