Spectral Emissivity of the 33-μ Band of Methane at Elevated Temperatures

The spectral emissivity of the ν3 band of methane was measured at temperatures of 297, 673, and 923 K. Use was made of absorption cells of various lengths in order to obtain curves of growth. Application of the Goody statistical band model to small frequency intervals within the band allowed the spectral band parameters to be obtained at the above-mentioned temperatures. The spectral absorption coefficient was found by two independent methods: by multiplication of the spectral-band parameters and by direct observation of the transmittance in the linear region. The integrated band intensity was also derived as a function of temperature up to 923 K.