High-resolution absorption coefficient and refractive index spectra of carbon monoxide gas at millimeter and submillimeter wavelengths

The use of dispersive Fourier transform techniques in interferometry allows the measurement of absorption coefficient and refractive index spectra with great precision. This paper presents the absorption coefficient and refractive index spectra of carbon monoxide (CO) gas at millimeter and submillimeter wavelengths. To assess rotational lines of CO, the gas was measured at four different pressures, giving insight into the behavior of the spectral lines with varying parameters. The measurements in this study demonstrate that varying the pressure of the gas affects only the amplitude of the absorption lines and not their exact position. This is critical in air pollution studies when trying to single out a specific gas from a field sample with unknown constituents