High sensitivity cavity ring down spectroscopy of N2O near 1.22 µm: (II) 14N216O line intensity modeling and global fit of 14N218O line positions

•Line parameters of two new 14N218O bands centered at 7966 cm−1 and at 8214 cm−1.•Refined sets of the 14N216O effective dipole moment parameters for ΔP=13,14 series.•Global modeling of 14N218O line positions and intensities in the 12-8231 cm−1 range.•5800 observed of 14N218O line positions reproduced with RMS=0.0016 cm−1.•List of 14N218O line parameters in the 0- 10,700 cm−1 spectral range.

In a recent work (Karlovets et al., 2016 [1]), we reported the measurement and rovibrational assignments of more than 3300 transitions belonging to 64 bands of five nitrous oxide isotopologues (14N216O, 14N15N16O, 15N14N16O, 14N218O and 14N217O) in the high sensitivity CRDS spectrum recorded in the 7915-8334 cm−1 spectral range. The assignments were performed by comparison with predictions of the effective Hamiltonian models developed for each isotopologue. In the present paper, the large amount of measurements from our previous work mentioned above and literature are gathered to refine the modeling of the nitrous oxide spectrum in two ways: (i) improvement of the intensity modeling for the principal isotopologue, 14N216O, near 8000 cm−1 from a new fit of the relevant effective dipole moment parameters, (ii) global modeling of 14N218O line positions from a new fit of the parameters of the global effective Hamiltonian using an exhaustive input dataset collected in the literature in the 12-8231 cm−1 region. The fitted set of 81 parameters allowed reproducing near 5800 measured line positions with an RMS deviation of 0.0016 cm−1. The dimensionless weighted standard deviation of the fit is 1.22. As an illustration of the improvement of the predictive capabilities of the obtained effective Hamiltonian, two new 14N218O bands could be assigned in the CRDS spectrum in the 7915-8334 cm−1 spectral range. A line list at 296 K has been generated in the 0-10,700 cm−1 range for 14N218O in natural abundance with a 10−30 cm/molecule intensity cutoff.