Fig. 3: Pit depth as a function of time.

Plots of pit depth as a function of exposure time are provided for six pits in (a) and (b). No change in the maximum depth of any of the pits was observed after 81 h of exposure, including Pit 6. All depth measurements are ± 3.0 μm, see the first and last datapoints plotted for Pits 1 and 5. 3D renderings of pit 6 at three different time steps are shown; images are at different scales. The scale bar for the insets in (b) is 15 μm. Error bars represent measurement uncertainty in depth and time as described in the “Methods”.