published by the Kabengi group. These data indicate that the reversibility condition required for an adsorption isotherm analysis, described further below, is met for all three cations. Fig. also shows the apparent signature of Stern and diffuse layer interactions we reported in 2021 for ionic strength jumps at constant pH. In that work, we found that under certain experimental conditions, the SHG intensity recorded when jumping the ionic strength from 100 mM NaCl to 10 µM NaCl at pH 5.8 undergoes a maximum at early times and then a signal reduction at longer times.