Fraction of 4 keV Li ions backscattered from pure elemental targets. Symbols connected by a solid line are measurements of individual yields relative to the yield of a stainless steel retainer (relative BI yield), with error bars indicating single standard deviation combined uncertainty. Dashed line is a Monte Carlo calculation of the fraction of ions backscattered (BI fraction) [Reprinted from Ref. 163, “Scanning ion microscopy with low energy lithium ions,” by K.A. Twedt, L. Chen, and J.J. McClelland, Ultramicroscopy 142, 24 (2014), copyright 2014, with permission from Elsevier].