Spectroscopic Diagnostics Of Active Species And Their Environmental Chemical Process Of O₂, N₂, CO₂ In Cold Plasma

Although low temperature plasma has great advantage in treating gaseous organic pollutants, which are low in concentration, great in quantity, numerous in varieties, and oxygen generating by decomposing CO2. Some solved difficultly problems are still existing. They are how to inhibit harmful byproducts and enhance selectivity of reactions. There are some subjects, such as the mechanism of plasma chemical reaction, the change laws of gas components, and the rule of reactions of active species.The main purposes in this thesis are going to study the varieties, energy characteristics, chemical activity, the change laws in concentration, and chemical reactions of active species generated in discharges. The main researches are arranged following.1. The active species in oxygen dielectric barrier discharge mainly were excited oxygen atoms (9.15~15.78 eV), excited oxygen molecules and oxygen molecular ions (>15 eV). The OH Free Radical and more energic oxygen ions O+ exist in damp oxygen DBD. It has been affirmed that the oxygen atom dissociated from molecule one is the dominant species to producing a serial of higher excited state of oxygen atom and the ionized oxygen molecules.2. The active species in DBD of oxygen mainly were various excited nitrogen molecules (6~11 eV) and a spot of N2+, NO, excited nitrogen atoms. The concentration of NO was decreased by increasing the dischare frequency.3. In DBD of the N2/O2 mixture, with increasing concentration of oxygen, the quintuple states nitrogen molecules and NO were decreasing quickly, and the concentration of was increased obviously, and the electron temperature was ncreased markedly. Therefore, the many more energic active species and energic electron generated in N2/O2 discharge were beneficial to enhance the efficiency of treating pollutants.4. The active species in DBD of CO2 mainly were excited CO, CO2+ and O. Carbon dioxide can be decomposed into carbon monoxide, oxygen and carbon in DBD that is a gentle discharge.5. The results of Quantum Chemistry Calculation showed that the triplet states decomposing path was the most possible in low energy discharge systems.