Infrared spectroscopy at high temperature : N₂- and O₂-broadening coefficients in the ν₄ band of CH₄

In the present work, we have developed a high-temperature absorption cell for infrared spectroscopy. This absorption cell can contain gases of the room temperature up to 650 K without temperature gradient. The construction of the cell and its technical features are described in detail in this paper. In order to demonstrate the feasibility and the interest of the cell, we have measured the N<inf>2</inf>-, O<inf>2</inf>- and air-broadening coefficients of, respectively, six and three absorption lines in the ^ν4 band of methane at four temperatures (350, 425, 500, 575 K). The measurements of these coefficients was realized with a tunable diode-laser spectrometer. The line parameters were obtained by fitting to the experimental profile the Voigt line shape and the Rautian and Galatry models taking into account the collisional narrowing. For these lines, the n parameter of the temperature dependence has been determined.