No abstract

We present the second part of the investigation of the high sensitivity absorption spectrum of nitrous oxide by CW-Cavity Ring Down Spectroscopy near 1.5 lm. In a first paper [A.. 244 (2007) 33-47] devoted to the 6000-6833 cm À1 region, more than 6000 line positions of five isotopologues ( 14 N 2 16 O, 15 N 14 N 16 O, 14 N 15 N 16 O, 14 N 2 17O, and 14 N 2 18 O), were rovibrationally assigned to a total of 68 bands. The achieved noise equivalent absorption (a min $ 2 · 10 À10 cm À1 ) allowed for the detection of lines with intensity weaker than 2 · 10 À29 cm/molecule. In this contribution, the investigated region was extended down to 5905 cm À1 and additional recordings allowed accessing small spectral sections uncovered in our preceding recordings. A deeper analysis based on the predictions of the effective Hamiltonian model has allowed assigning a total of 3149 transitions and lowering the percentage of lines left unassigned from 51% to 28%. It led to the analysis of 35, 6, 7, and 6 bands for the 14 N 2 16 O, 15 N 14 N 16 O, 14 N 15 N 16 O, and 14 N 2 18 O isotopologues, respectively. Forty-two of these 54 bands are newly observed, while the rotational analysis of the twelve others is significantly extended and improved. Most of the bands were found unperturbed and their line positions could be reproduced within the experimental uncertainty (about 1 · 10 À3 cm À1 ). The corresponding spectroscopic parameters are reported. Local rovibrational perturbations induced by either intrapolyad or interpolyad couplings were found to affect five hot bands of 14 N 2 16 O. Their detailed analysis is presented.