Several bands of CO intercombination systems have been recorded for the first time under high-resolution Fourier transform spectroscopy: B1Σ+-e3Σ-(0-1), B1Σ+-d3Δi(0-5), and B1Σ+-d3Δi(0-12), B1Σ+-a′3Σ+(0-14), and B1Σ+-a′3Σ+(0-17). The emission spectrum was produced from an electric discharge through a mixture of formic acid and helium. Observed wavenumbers of rotational lines (0 < J < 19) are presented. The line position uncertainties range from 0.001 to 0.02 cm-1, depending on the transition intensity. These bands are forbidden by electric-dipole selection rules and borrow intensity from the main Angstrom B1Σ+-A1Π system, via spin-orbit interactions. It is shown that these data are consistent with recent studies of perturbations arising in the A1Π levels. In addition, the mixing coefficients, which represent the fractional A1Π character of each line, are also reported.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry