内容摘要：In simple diatomic molecules, Rydberg states inherit the clean hydrogen-like structure of their atomic counterparts while introducing nuclear degrees of freedom that open entirely new avenues for quantum control, precision measurement, and fundamental tests of physics. A central focus of this talk is superexcited states of molecular hydrogen, where Rydberg mani folds embedded in the ionization continuum decay through competing channels: autoionization to H⁺₂, ion-pair formation (H⁺ + H⁻), and neutral dissociation. Using a (1+2) REMPI scheme combined with time-of-flight spectroscopy and velocity-map imaging, we resolve product channel branching ratios, kinetic-energy-release spectra, and fragment anisotropies, providing stringent benchmarks for coupled-channel and scattering calculations. Beyond benchmarking, these superexcited states are directly relevant to H+ 2 formation pathways in the early universe and, crucially, open a route toward the controlled synthesis of H− 2: a homonuclear molecular anion of antimatter that remains experimentally out of reach. A second theme is the use of Rydberg excitation followed by pulsed-field-ionization for state selective preparation of molecular ions. For homonuclear diatomics, a vanishing electric dipole moment prevents fluorescence-based rotational state control, making this the primary route to defined rovibrational populations. State-selective preparation of H+ 2 gives access to weakly bound vibrational states near the dissociation threshold, which carry enhanced sensitivity to a variation of the proton-to-electron mass ratio, as well as to ortho-para mixing induced by the hyperfine interaction. Finally, I will briefly outline how the near-diagonal Franck-Condon factors of Rydberg transitions in He2 make this molecule a compelling candidate for laser cooling. Ultracold He₂ would be the lightest and simplest laser-cooled few-electron molecule and the first laser-cooled homonuclear diatomic. In parallel, He⁺₂ serves as a quantum sensor for the static polarizability of atomic helium, required for quantum-based pressure standards