High accurate peak positions for calibration purposes with the lowest fundamental bands ν2 of N2O and CO2

The lowest fundamental vibration rotation bands ν2 of nitrous oxide (N2O) and carbon dioxide (CO2) have been measured with a Fourier transform spectrometer at the resolution of 0.001 cm−1. The spectra have been calibrated with the high accurate peak positions of the carbonyl sulfide (OCS) ν2 band, which has been recently produced as a candidate for a secondary standard by calibrating first the 2ν2 band with the CO2 laser bands around 10 μm and then transferring the calibration to ν2 with the internal energy levels of OCS. In the present work the OCS ν2 and ν1 bands were measured together with the spectra of N2O and CO2. Then the OCS ν1 band was measured by calibrating it with the 2ν2 band of OCS. The linearity of the wavenumber scale was checked by comparing the corresponding line positions in the OCS ν1 band in these two separate measurements. The absolute accuracy of the ν2 band centers of N2O and CO2 were evaluated to be 6.8 × 10−6 and 8.4 × 10−6 cm−1, respectively.