Transient Molecular-Ion Formation in Rydberg-Electron Capture

Resonance structure has been observed in total cross sections for the capture of an electron from a Rydberg-state atom by a singly charged projectile with speed $v_{\mathrm{ion}}$ comparable to the Bohr velocity $v_e$ of the target electron. Prominent peaks in the data at reduced velocities $\tilde{v}{=v}_{\mathrm{ion}}{/v}_e=0.8\mathrm{}$ and 0.5 result from two distinct capture mechanisms in which the target electron passes once or three times, respectively, through the midplane between the nuclei. The three-swap peak at $\tilde{v}=0.5\mathrm{}$ marks the high-velocity limit of molecular-ion formation in which the electron is shared between the two charge centers. This result illustrates that new paradigms for collision dynamics may emerge when reactions are examined at or near the correspondence principle limit.