Fig 4.
Depth profile of the positive [M + H] + and negative [M − H] − molecular secondary ions of Irganox 1098 (m/z 637 and 635) and Irganox 1010 (m/z 1178 and 1176) across the NPL irganox multilayer measured with an HCl doped 20 keV Ar3k+ (1.25% HCl) cluster ion beam applied for erosion and data acquisition. For a logarithmic plot of all recorded signals see supporting Fig S 5.