The microwave spectrum of propiolactone has been studied in the 18ndash;34 kmc region. Analysis of the data obtained leads to the conclusion that the ring is planar and ang;HCH=112deg;. Satellite spectra are observed and attributed to the outhyphen;ofhyphen;plane ring bending mode with a first excited state 120 cmmdash;1above ground. Quantitative Stark effect studies support the planarity assumption and lead to a dipole moment of 4.18plusmn;0.04 d. The possible orientations of the dipole are considered.
展开▼
