Knowledge Bank

Single rotational levels photoselected in the strongest bent $B2A\prime$ state of HCO serve as intermediate states in double resonance transitions to Rydberg states built on higher vibrationally excited levels of the linear $HCO+$ core. Frank-Condon factors for the bent-to-linear transitions discriminate against resonances converging to lower lying vibrational states. Widths and intensities of multiple quantum vibrational autoionization resonances are affected by the level of core excitation.