Research On Spectral Line Profile And Line Width Of High-Resolution (Saturation) Molecular Spectra And Its Application

Studies of the linewidth, the line strength and the line profiles of molecular spectrum are of considerable importance both in theory and in experiment. From this information molecular structure constants and the conditions of the surrounding environment of this molecule can be deduced. Therefore, there have been wide applications of line shape theory to a variety of subjects including chemical kinetics, biomedicine, astrophysics and meteorology. The key of these applications is the appropriate line shape function and the determination of the precise linewidth of the molecular spectrum. This dissertation focuses on both experimental and theoretical studies about spectral line profile and linewidth.A CO laser magnetic resonance spectrometer was made in co-operation and employed to obtain the ultra-high-resolution spectrum of NO thus to resolve its hyperfine structures and Lambda-splittings. This measurement provides a very good experimental data for the theoretical analysis.The theoretical study focuses on the Voigt spectral line profile analysis and calculation. Through the comparison of the theories for calculating Voigt profile made by previous authors, we present an analytical sum formula to approximate the Voigt profile and hence improve the efficiency of its calculation. This empirical formula is the simplest approach and has the quickest convergence. It can be applied to the analysis of spectra broadened by a single mechanism or by many mechanisms. Using this approximate formula, we composed a general simulation program and a fitting program and simulated and analyzed the LMR spectra of NO. The results are in very good agreement with full quantum Hamiltonian calculation. In order to automatically obtain the spectral line positions and line intensities, we also designed programs to realize the spectral analysis automation. These programs have been proved to be efficient assistant tools for the analysis of large and complicate experimental spectral data.Using the saturation absorption LMR technique, the precise measurement of linewidth and the pressure broadening coefficient of NO has been made by considering the experimental corrections. The pressure-broadening coefficient of ¹⁵N¹⁶O by ¹⁴N¹⁶O was extracted by fitting the...