Observation of high-angular-momentum Rydberg states ofH2in a fast beam

Rydberg states of ${\mathrm{H}}_2$ with n=10, L=3–6, formed in charge-capture collisions of (11 KeV) ${\mathrm{H}}_2$ ${\mathrm{}}^{+}$ ions, are resolved spectroscopically by laser excitation of the 10→27 electronic transition, detected by Stark ionization of the upper state. Measured level positions are in good agreement with a priori predictions. The Rydberg spectrum identifies participating ${\mathrm{H}}_2$ ${\mathrm{}}^{+}$ core states as ν=0 (only) and R=0–3, but relative line intensities appear anomalous.