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This study employs comb-based Fourier-transform spectroscopy to achieve absolute frequency measurements of the CO fundamental band and derive high-precision collisional line-shape parameters for the CO-Ar system. By utilizing a stable mid-IR optical frequency comb and advanced noise suppression techniques, the researchers attained line-center fitting errors below 0.00001 cm$^{-1}$, with transition frequencies aligning closely with the HITRAN database. The results include reliable collisional parameters for approximately 40 P- and R-branch lines, establishing a significant experimental benchmark for CO-Ar line-shape modeling.
Achieving line-center fitting errors below 0.00001 cm$^{-1}$ sets a new standard for precision in molecular spectroscopy.
We report absolute frequency measurements of the CO fundamental band, together with high-precision Ar-induced collisional line-shape parameters using comb-based Fourier-transform spectroscopy. High-quality spectra were obtained with a stable mid-IR optical frequency comb source and careful suppression of technical noise. By applying analysis methods that fully exploit the advantages of optical frequency comb spectroscopy, precise frequency calibration and robust multi-line fitting were achieved, resulting line-center fitting errors below 0.00001 cm$^{-1}$ for most transitions. The measured transition frequencies agree with HITRAN within 0.0001 cm$^{-1}$, supporting the reliability of the semi-empirical database. Multi-line fits using a speed-dependent Voigt profile yield collisional parameters for approximately 40 P- and R-branch lines, providing a reliable experimental benchmark for CO-Ar line-shape modeling.
