Infrared laser spectroscopy using a long pathlength absorption cell

The authors developed two very long pathlength absorption cells to be used in conjunction with diode lasers. They were designed to operate at controlled temperatures with the optical pathlength variable up to approx. 1,5 Km. Not only very low sample pressures are used for studies with such cells but also the spectroscopic sensitivity is enhanced over conventional methods by a factor of 103 to 104. In this paper they present some analytical aspects of the diode laser spectroscopy using the long pathlength absorption cells in the areas of absorption line widths, pressure broadening coefficients, isotope composition measurements and trace impurity analysis