High sensitivity CW-cavity ring down spectroscopy of N2O near 1.5 μm (III)

We present the third part of the investigation of the high sensitivity absorption spectrum of nitrous oxide by CW-Cavity Ring Down Spectroscopy near 1.5 μm. In the two first contributions (A. Liu, et al., J. Mol. Spectrosc. 244 (2007) 33-47 and A. Liu, et al., J. Mol. Spectrosc. 244 (2007) 48-62) devoted to the 5905-6833 cm−1 region, more than 9000 line positions of five isotopologues (14N216O, 15N14N16O, 14N15N16O, 14N217O and 14N218O), were rovibrationally assigned to a total of 115 bands, most of them being newly detected. The achieved sensitivity (αmin∼3 × 10−10 cm−1) allowed for the detection of lines with intensity weaker than 2 × 10−29 cm/molecule. In this contribution, the investigated region was extended up to 7066 cm−1. The analysis based on the predictions of the effective Hamiltonian model has allowed assigning about 1500 transitions to 17, 1, 2 and 1 bands of the 14N216O, 14N15N16O, 15N14N16O and 14N218O isotopologues, respectively. Eleven of these 21 bands are newly reported, while the observations of the transitions are extended to higher J values for most of the others. The band by band analysis has allowed reproducing the measured line positions within the experimental uncertainty (about 1 × 10−3 cm−1) and determining the corresponding spectroscopic parameters. A detailed analysis of the rovibrational perturbations affecting three bands of 14N216O is presented.