Infrared Line Strengths and Pressure Broadening Coefficients in the ν12 Vibrational Band of Hydrazine Measured by Infrared Tunable Diode Laser Spectroscopy

Infrared line positions, linestrengths, and pressure-broadening coefficients are required to determine absolute trace gas concentrations from high-resolution absorption spectra. We have measured these values for the infrared absorption lines in the ν12 band (antisymmetric wag) of hydrazine between 965.4 and 965.7 cm−1 using a high-resolution tunable diode laser system with 0.0006 cm−1 spectral resolution and an 18-m path length multiple pass absorption cell. A continuous flow of hydrazine diluted to 100–500 parts per million in nitrogen at pressures between 0.1 and 50 Torr was used to prevent decomposition in the sampling cell. The total integrated linestrength from 965.477 to 965.663 cm−1 is (2.20±0.14)×10−20 cm2 molecule−1 cm−1. The strongest line in this region at 965.5557 cm−1 has a strength of 2.8×10−21 cm2 molecule−1 cm−1. The only isolated line in this region, at 965.4905 cm−1, has a broadening coefficient by nitrogen of 0.11±0.01 cm−1 atm−1 at 295 K. These results are compared to the qualitative high resolution spectra determined by other researchers using FTIR spectroscopy, and have been used to construct a HITRAN-format line list that can be used both to spectroscopically distinguish hydrazine from other components and to determine its concentration in a complex gas phase mixture. [Copyright &y& Elsevier]