High resolution absorption and magnetic rotation studies of the system of formaldehyde-d1

The 410, 430, and 410610 bands of the [Formula: see text] system of HDCO have been reinvestigated in absorption under high resolution. While the results confirm the earlier rotational analyses of Job et al. (1969), arguments are advanced for changing the assignment of the 777 cm−1 interval from ν3′ to ν6′.The bands have also been studied in magnetic rotation. Most of the activity is attributed to the magnetic dipole transition moment between the ground and excited singlet states, but some activity is assigned to singlet–triplet interactions. For the 430 band, a possible mechanism with ΔJ = 0, ΔN = 0, and ΔKa = 0 selection rules has been deduced.