Norbornadiene is a polycyclic isomer of toluene. Transition frequencies were taken from
(1) B. Vogelsanger and A. Bauder, 1988, J. Mol. Spectrosc. 130, 249.
Initial estimates of the quartic distortion parameters were taken from an MP2 quantum-chemical calculation by
(2) H. S. P. Müller, 2021, unpublished.
The data set is quite limited, in particular concerning transitions with ΔJ ±1. The calculations were therefore truncated at 200 GHz and at J = 50. The calculations should be sufficient for searches in cold environments. Transition frequencies with J > 10 should be viewed with caution.
Spin-statistical weight ratios have been ignored because of the proximity to 1 : 1.
The dipole moment is from (1).