Dipole moment of cis-glyoxal in the 1B1 electronic state from static and modulated stark spectroscopy

The Stark effect on the ¹B₁ - ¹A₁ transition of cis-glyoxal near 487.5 nm is investigated. The effect arises from interaction between appropriate pairs of accidentally degenerate rotational levels. By using static and modulated electric fiels a value of 2.3 ± 0.5 D for the dipole moment along the b-axis of the molecule in the ¹B₁ state is obtained.