Excitation Characteristic Analysis Of N In Solid Materials By Using LIBS Molecular Information

As one of the most important nonmetallic elements,nitrogen element exists in a variety of detecting objects.There are various forms,mainly in the form of organic and inorganic nitrogen As a new kind of detection method,laser-induced breakdown spectroscopy(LIBS)gets more and more attention because of its many advantages,however there are some difficulties in the application of LIBS in detecting nitrogen element due to the excitation characteristics and physical properties of the element.In this thesis,LIBS technology was applied in the detection of nitrogen.Based on the deep understanding of the current domestic and international research,the excitation characteristics of inorganic nitrogen and organic nitrogen in the solid samples were researched from the perspective of molecular spectroscopy.For organic nitrogen,the differences of atomic spectrum and CN molecular spectral characteristic in different atmosphere were deeply studied through theoretical and experimental analysis.Besides,the test conditions were optimized through the analysis of the laser energy and plasma temperature and the feasibility of detecting nitrogen element in the organic sample was studied by analyzing CN molecular spectral correlation spectrum and detection limit.As to the inorganic nitrogen,it was found that CN molecular spectral line could be applied in quantitative analysis of inorganic nitrogen by adding plenty of organic carbon through testing experiments and the relationship of CN molecular spectral line and spectral line related to C formation mechanism was analyzed theoretically.In addition,according to the excitation characteristics of organic and inorganic nitrogen,the spatial-temporal evolution characteristics of C and N relevant spectral lines were analyzed.Then the different forms of nitrogen were distinguished and the detection delay time and spatial height were optimized according to the spatial-temporal evolution characteristics of C and N relevant spectral lines.Finally,the results of the whole research works were summarized and the directions for the further studies were suggested..