The experimental lines are from
(1) R. E. Hilliger and M. W. P. Strandberg, 1951, Phys. Rev. 83, 575,
and from
(2) P. Helminger, R. L. Cook, and F. C. De Lucia, 1971, J. Mol. Spectrosc. 40, 125.
The latter work also contains some data from
(3) C. A. Burrus, unpublished.
Also included in the fit are far-infrared transitions from
(4) C. Camy-Peyret, J.-M. Flaud, L. Lechuga-Fossat, and J. W. C. Johns, 1985, J. Mol. Spectrosc. 109, 300.
Two frequencies from (1) fitting already poorly in (4) were omitted from the fit as were a small number of FIR frequencies with large residuals from (4). As usually, the FIR transition frequencies have not been merged. The predictions should be reliable as long as the uncertainties do not exceed 5 MHz by far.
The dipole moment is from
(5) R. Viswanathan and T. R. Dyke, 1984, J. Mol. Spectrosc. 103, 231.