Resonance ionization spectroscopy of HCO and DCO. I. The 3p 2Π Rydberg state

Resonance two-photon ionization (R2PI) spectroscopy has been used for medium resolution studies of HCO and DCO at wavelengths from 208 to 222 nm. Vibronic analysis of subband positions originating from both A′ and A″ symmetry components of the 3p 2Π Rydberg states of HCO and DCO yields values for the Renner–Teller parameter Ε, dipolar vibronic parameter gk, quartic anharmonicity constant g22, harmonic bending vibrational frequency ω2, anharmonicity constant x22, and spin–orbit splitting constant A. Values of the harmonic frequencies ω2 and anharmonicity constants x22 for the bending vibrations of the HCO and DCO X̃ 2A′ ground states are also determined. Previously unidentified two-photon subbands, thought to be excitations of the 3s 2Σ+ Rydberg state, are assigned to the symmetric A′ component of the 3p 2Π state.