Resonance ionization spectroscopy of the 3p Rydberg and B valence states of HCO and DCO

Abstract

Resonance two-photon ionization (R2PI) spectroscopy has been used for medium resolution studies of HCO and DCO. Vibronic analysis of subband positions for both A′ and A″ symmetry components of the 3p2Π Rydberg states of HCO and DCO yields values for the Renner-Teller parameter ε, dipolar coupling constant g k , quartic anharmonicity parameter g22, harmonic bending vibrational frequency ω2, anharmonicity constant x22, and spin-orbit splitting constant A. Values of the harmonic frequencies (ω 2 and anharmonicity constants x22 for the bending vibrations of the HCO and DCO χ ˜ 2 A ′ ground states are also determined. Term values, the three harmonic vibrational frequencies, and six anharmonicity constants are measured for the B ˜ 2 A ′ states of both molecules. Fundamental frequencies of 1382 cm−1 and 1213 cm−1 for HCO and DCO, respectively, are identified with the B ˜ state bending vibration; frequencies of 2597 cm−1 for HCO and 1944 cm−1 for DCO correspond to CH (CD) stretching, while the lowest fundamental frequencies of 1066 cm−1 for HCO and 922 cm−1 for DCO correspond to the vibration of singly bonded C-O.