The absorption spectrum of acetylene near 1 µm (9280–10,740 cm-1) (II): Line intensities

Abstract

In a companion paper, rovibrational assignments of acetylene in the 9280–10,740 cm–1 region were extended on the basis of a long path absorption spectrum recorded by Fourier-transform spectroscopy. Thirty-three and seven bands of 12C2H2 and 12C13CH2 were assigned, respectively, twelve 12C2H2 bands being newly assigned. In the present work, the vibrational transition dipole moments squared and Herman–Wallis coefficients of the bands are derived from a fit of the measured intensity values. An empirical recommended line list is provided with positions calculated using empirical spectroscopic band parameters and intensities calculated using the derived Herman–Wallis coefficients. As a result the constructed line list in the 9450–10,740 cm-1 region includes a total of 2774 lines belonging to 32 bands of 12C2H2 and seven bands of 12C13CH2. For comparison the HITRAN database in the same region includes 305 lines of 4 bands, all belonging to 12C2H2. The recommended acetylene line list is compared to the HITRAN line list and to the Acetylene Spectroscopic Database (ASD) constructed using the global effective operator approach.The measured bands belong to the ΔP = 15 and 16 series of bands where P = 5V1 + 3V2 + 5V3 + V4 + V5 is the polyad quantum number. An improved set of ΔP = 15 effective dipole moment (EDM) parameters is derived from a fit of the measured intensity values. The ΔP = 16 EDM parameters are derived for the first time. The derived sets of EDM will allow extending the Acetylene Spectroscopic Database at higher energy.