High-resolution absorption measurements of NH₃ at high temperatures: 500–2100cm⁻¹

High-resolution absorption spectra of NH₃ in the region 500–2100 cm ^-1 at temperatures up to1027 1C and approximately atmospheric pressure (1013±20 mbar) are measured. NH₃ concentrations of 1000 ppm,0.5% and 1% in volume fraction were used in the measurements. Spectra are recorded in high temperature gas flow cells using a FourierTransform Infrared (FTIR) spectrometer at a nominal resolution of 0.09cm^-1. Measurements at 22.7 °C are compared to high-resolution cross sections available from thePacific Northwest National Laboratory (PNNL). The higher temperature spectra are analysed by comparison to a variational line list, BYTe, and experimental energy levels determined using the MARVEL procedure. Approximately 2000 lines have been assigned, of which 851are newly assigned to mainly hot bands involving vibrational states as high as _v2=5.