Minimum depth electron probe x‐ray microanalysis as a means for determining the sulphur content of the human hair surface

By using incident electron energies as low as 3 keV it has been shown both theoretically and practically that the maximum depth for the excitation of sulphur Kα x‐rays from a sulphur‐containing proteinaceous solid can be restricted to 110 nm. This approach has been used to determine the concentration of sulphur in the immediate surface of human hair, and more particularly associated with the A‐layer subcomponent of the hair cuticle. The value obtained was 11.8 weight % (± 0.92, n = 10).