High accurate peak positions for calibration purposes with the lowest fundamental bands ν2 of N 2O and CO 2

Abstract

The lowest fundamental vibration rotation bands ν 2 of nitrous oxide (N 2O) and carbon dioxide (CO 2) 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) ν 2 band, which has been recently produced as a candidate for a secondary standard by calibrating first the 2 ν 2 band with the CO 2 laser bands around 10 μm and then transferring the calibration to ν 2 with the internal energy levels of OCS. In the present work the OCS ν 2 and ν 1 bands were measured together with the spectra of N 2O and CO 2. Then the OCS ν 1 band was measured by calibrating it with the 2 ν 2 band of OCS. The linearity of the wavenumber scale was checked by comparing the corresponding line positions in the OCS ν 1 band in these two separate measurements. The absolute accuracy of the ν 2 band centers of N 2O and CO 2 were evaluated to be 6.8 × 10 −6 and 8.4 × 10 −6 cm −1, respectively.