Photoionization spectrum of the B2A′ state of HCO

Formyl radicals, excited to specific rovibrational levels of the strongly bent B2A′ state are photoionized to form vibrationally excited states of the linear cation by the absorption of a tunable pulse of ultraviolet light from a second laser. Strong and essentially continuous photoionization spectra, which appear at intervals lying 7000 and 12 000 cm−1 above the adiabatic threshold, establish that formyl radicals can be efficiently ionized with a large geometry change at both energies. Non-Franck–Condon intensities suggest multiquantum pathways for vibrational autoionization.