Acetylene intensity measurements using a tunable laser spectrometer

High resolution knowledge of acetylene spectral features is a prerequisite for quantitative analyses in planetary atmospheres of Titan, Saturn, and Jupiter. Line and band intensity measurements on ¹²C₂H₂ and ¹²C¹³CH₂ around 13.7 micrometers were performed with spectral resolution of 0.0005 cm^-1, using a tunable diode laser spectrometer. Band intensities extracted from line intensity measurements, in units of cm^-2atm^-1 at 296 K, are: 565 for the v₅-fundamental band of ¹²C₂H₂, 24.6 for the (v₄+v₅)^-o-v₄¹ band of ¹²C₂H₂, and 581 for the v₅-fundamental band of ¹²C¹³CH₂.

Due to the sensitivity of the technique, pressure self-broadening of the order of 0.15 cm ¹ per atm. for the half-width (0.0002 cm¹ per torr), and pressure shift of the order of -0.003¹ at 1 torr were also observed. These latter results have to be confirmed by further measurements.