Extended Data Fig. 5: The effect that changing the diameter of the cylindrical region of interest has on the sputter coated Cr and olivine interface and on counting statistics under the peak.

a, The 42 nm cylindrical region of interest used to produce the concentration profiles from the APT dataset Itokawa3 Extended Data Fig. 3J-L. b, A 3 nm cylindrical region of interest from the APT dataset Itokawa3. c, Corresponding concentration profiles in atomic percent (at. %) for Cr (black line) and H (red line) from the 42 nm region of interest and sum Cr (grey line) and H (yellow line; including molecular ions) concentration profiles from the 3 nm wide cylinder. We note that the Cr-olivine interface is sharper in the 3 nm wide cylinder but it comes at the expense of the counting statistical uncertainty of the measurement. Line widths have been adjusted to represent the 1 sigma uncertainty and depth profiles are absolute abundances not relative concentrations.