Vol. 11, issue 04, article # 5

Abstract:

A new method is proposed for laser monitoring of the atmospheric pollution: path multicomponent molecular diagnostics using IR double-resonance saturated absorption spectroscopy. The essence of this method is preliminary excitation of a selected vibrational-rotational level of detected molecules and application of the procedure of differential absorption on an adjacent "hot" transition. With the help of the HITRAN-92 database, a search has been conducted for vibrational-rotational transitions suitable for the application of the proposed method to simple molecules. Formulas for the determination of concentrations of the detected molecules have been derived. Sensitivity of measurements by the proposed method has been estimated and a comparison with the traditional method of differential absorption has been made. Altitude and temporal dependences of the saturation intensity of the vibrational-rotational transition have been calculated. Saturation conditions on the path with consideration for the spatial orientation of a pumping beam and its initial focusing have been determined.