Figure 3

Performance of the empirical (Eq. 1) and theoretical models (Eqs. 17, 23, 24, and 25) against the average number of helium atoms in a bubble of a given size for helium atoms at distances greater than 4 nm beneath the original surface (i.e., the surface’s location prior to plasma exposure). All “averages” based on only one point are denoted in grey rather than black and lack error bars. Error bars denote 95% confidence intervals.