Reaction System Of Some Small Molecule Scattering Resonance State And Isotope Effect Theory Research

Chemical reaction kinetics has experienced three stages over the past 100 years. The first stage (1900-1970) is macrodynamics period with focus on the reaction velocity constant; the second stage (1970-2000) features the dynamics of state-to-state elementary reactions, i.e., the impact study of intermolecular rovibrational states on the multimodal and directional distributions of the product; the third stage (from 2000 to the present) marks the study of scattering resonance state, or in short, the dynamics of resonance, emphasizing on the investigation of eigenstate and eigenvalue of the activated complex in transition state. According to the requirements of experimental measurement and theoretical calculation, the data of resonance energy and resonance lifetime are necessary to further the understanding of the formation mechanisms of resonance state and to provide clearer and closer insights into the overall process of chemical reactions. It aims to save energy, to maximize reaction velocity and to construct or manufacture the lazer of activated complex in transition state.The study of scattering resonance state which has brought chemical kinetics into a new era, is undoubtedly the frontier of chemistry. The two concerns of the study are the formation mechanisms of scattering resonance state and the calculations of resonance lifetime and resonance energy. The dissertation applys the concept and construction approach of the partial potential surface put forward by zhengting Cai etc., constructs several partial potential surfaces with symmetrical and asymmetrical heavy-light-heavy systems, or more complicated reaction systems, explains the formation mechanisms of scattering resonance state, and provides the data of resonance energy. Unlike the full and reducing dimensional potential surfaces, the partial potential surface can disclose the underlying reason why the so-called "direct reaction" in the scattering resonance state doesn't exist in the course of minimum energy reaction, give a reasonable explanation for Neumark's high-resolution optical spectral separation of the precursory negative ions of the activated complex in transition state, and foster a correct prediction of the excitation function observed in the experiment of crossed molecular beam.The dissertation includes the following two aspects:The first issue is the concept and construction approach of the partial potential surface. Several partial potential surfaces with the molecular reaction systems are constructed by the method of ab initio, including F+H₂â†'FH+H,F+HDâ†'FH+D, and F+HDâ†'FH+D; OH+H₂Oâ†'H₂O+OH, H¹⁸O+HOHâ†'H¹⁸OH+OH, and DO+HOHâ†'DOH+OH;Br+CH₄â†'HBr+CH₃ and Br+CD₄â†'DBr+CD₃; O(³P)+ CH₄â†'OH+CH₃. to explain the formation mechanisms of scattering resonance state based on the reaction process of these systems, to point out that the cause of the state is the depression in the transitional region, or called the dynamic Eyring lake, and to provide the data of resonance energy.The second issue is about the calculations of isotope effect of the following molecular reaction systems (F+H₂â†'FH+H,F+HDâ†'FH+D and F+HDâ†'FH+D; OH+H₂Oâ†'H₂O+OH, H¹⁸O+HOHâ†'H¹⁸OH+OH and DO+HOHâ†'DOH+OH; Br+CH₄â†'HBr+CH₃ and Br+CD₄â†'DBr+CD₃; ), and the geometrical constructions of the complex collision of each reaction in the transition state. Therefore, it comes to an important conclusion that those geometrical constructions are exactly the same after the isotopic substitution, and more valuable conclusions are drawn after the comparison of the frequencies of those reactions after the isotopic substitution, the first resonance energy and the fist resonance lifetime. All these will serve as significant references for the theories of these reactions and for the relevant researchers.The study of scattering resonance state has become a new hot spot since 2000. GC.Schatz and R.N.Zare, the authorities in the research of molecular reaction dynamics, once made authoritative comments in some leading magazines. It is illustrative of the great prospect of this research field; and meanwhile it needs large quantities of human, material and financial resources in experiments (those of crossed molecular beam, optical spectral separation, and femtosecond technology, etc.) as well as in theories (those of potential surfaces and quantum scattering, etc.). Immature and incomplete our study may seem, it gets off to a good start and has achieved a satisfactory result. Hopefully, more researchers will make improvements in this area.