High resolution studies of magnetic optical activity in the 3A2–lA1 system of formaldehyde

Magnetic rotation spectra of the 3A2–1A1 system of formaldehyde have been photographed with high resolving power; the 1+–0 band has been studied in detail throughout its rotational fine structure. The magnetic circular dichroism (MCD) and birefringence (MCB) of this band have also been recorded. The results have been interpreted using the theory of Buckingham and Stephens and satisfactory agreement found. The magnetic optical activity arises primarily from A terms although some features which can be attributed to B terms have been identified.