Observation of the partial decay intoH0(n’=2) by excitedH−near then=3 and 4 thresholds

Two resonances in the photodetachment spectrum of ${\mathrm{H}}^{\mathrm{-}}$, one just below the n=3 threshold and the other just below the n=4 threshold, were observed decaying into ${\mathrm{H}}^0$(n’=2)+e. The n=3 resonance shows a preference for the n’=2 channel when compared with total-detachment measurements. Fano-line-shape fits give central energies of 12.652±0.003 eV for ${\mathrm{H}}^{\mathrm{-}\mathrm{*}\mathrm{*}}$(3) and 13.338±0.004 eV for ${\mathrm{H}}^{\mathrm{-}\mathrm{*}\mathrm{*}}$(4). These values are in good agreement with current theoretical calculations.