  A highly effective approach to the search for hypothetical new interactions
through isotope shift spectroscopy of hydrogen-like ions is presented. A
weighted difference of the g factor and ground-state energy is shown to assist
in the suppression of detrimental uncertainties from nuclear structure, while
preserving the hypothetical contributions from new interactions. Experimental
data from only a single isotope pair is required. Account is taken of the
small, subleading nuclear corrections, allowing to show that, provided feasible
experimental progress is achieved in UV/X-ray spectroscopy, the presented
approach can yield competitive bounds on New Physics electron coupling
parameters improved by more than an order of magnitude compared to leading
bounds from atomic physics.
