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Accepted · first revision · record

Title: Is the underscreening scaling exponent 3 universal across electrolytes?
Plain: Experiments suggest one simple power law describes how the shielding distance grows for many different concentrated salts. Whether the power is really the same number everywhere, and what that number is, would strongly constrain any explanation.
Precise: Define $n$ by $\lambda_S/\lambda_D \sim (a/\lambda_D)^n$ in the concentrated regime $a/\lambda_D >\sim 1$. Determine whether $n$ takes a single value across aqueous alkali halides, multivalent salts and ionic liquids, and whether that value is 3 as surface-force data suggest or the $n \sim 1.5$ range of bulk liquid-state theory. An answer is a measured or computed $n$ with error bars for at least three chemically distinct classes.
Settled by: Systematic measurements of $\lambda_{S}$ across salts and solvents with at least two independent techniques, fitted over a decade or more of $a/\lambda_{D}$.
Kind: well-posed
Answer type: value
References: (empty)
Literature status: contested
Status note: (empty)
Posed since: 2017