Precision frequency measurement of N2O transitions near 4.5 μm and above 150 μm

Frequency measurements are given for the 1000 ← 0000 band of N2O near 4.5 μm and for pure rotational transitions beyond 151.5 μm. The infrared measurements utilize a periodically poled lithium niobate (PPLN) based difference frequency generation (DFG) source locked to the saturated absorption center of an N2 O absorption line. The DFG frequency is calibrated by an optical frequency comb and an iodine hyperfine transition. We report 44 transitions ranging from J = 1 − 100 for both the P and R branches and the accuracy is better than 10 kHz for most transitions. In addition, 175 pure rotational transitions have been measured including 33 measurements with sub-Doppler precision (≤3 kHz), and 142 Doppler limited measurements. These are combined with other precision rotational and vibrational measurements to provide improved quantum mechanical parameters, as well as frequency calibration tables for the N2O bands near 4.5 μm.