Laboratory measurements of the infrared spectra of planetary atomospheric trace gases.

摘要

High-resolution measurements of the infrared spectra of CO broadened by CO, air, H₂, and CO₂ were performed at various temperatures using a Bruker IFS-120HR Fourier-transform spectrometer and a 0.8m long multireflection White cell and a 10.16cm cryogenic cell. A most generalized version of multi-spectral non-linear least-squares line fitting algorithm, so called simultaneous multi-spectra fitting (SMSF) algorithm was developed, by which various sets of spectra were able to be fitted simultaneously. Among them are (1) multiple spectra of pure CO sample and multiple spectra of mixtures of CO + air and CO + H₂, (2) multiple spectra of pure CO, pure CO₂, and CO mixtures with CO₂.; Absolute intensities, self- and air-broadened half-widths, and self- and air-induced line shifts were measured in the (3-0) band of 12C 16O at 298 K. The intensity of the band was determined to be (4.62 ± 0.06) × 10−22 cm/molecule at 296 K, which is 5% smaller than that of the HITRAN database. The square of the transition moment, |μ₀|2, of this band was deduced to be (1.712 ± 0.004) × 10−7 Debye2. H₂-broadened line widths and H₂-induced line shifts in the (1-0) and the (2-0) bands of 12C16O at temperatures between 83 and 302 K were measured. From these data their temperature dependence was determined. H₂-broadened line widths in the three bands do not show significant dependence on rotational quantum number except for the lines in the vicinity of the band centers. The line widths and line shifts were also measured in the (3-0) band at room temperature. CO₂ -broadened spectra of CO were measured in the (1-0) band at 201, 244 and 300 K and in the (2-0) and the (3-0) bands at 298K.; While the line widths are practically the same in the three bands in the self-, air-, H₂ and CO₂ spectra, the line shifts are progressively larger with the vibrational quantum number of the upper energy level. This study is the first comprehensive laboratory measurement at high resolution that reports the line parameters of CO broadened by H ₂ and CO₂ at low temperatures. These data can be readily used in the interpretation of observed lines of the atmospheres of the planets Jupiter, Saturn, Venus, and Mars.