Halogen Azides The Xn <sub> 3 </ Sub> (x = F, Cl, Br, I) The Preparation, Pes And Quantum Theory

Photoelectron Spectroscopy was established at the end of 1960's. At the beginning of 1980's, the first two-chamber super-vacuum ultraviolet photoelectron spectroscopy machine was built in China. It has been widely used for the study not only on the stable species, but also on the transient species. The development of the technique of Ultraviolet Photoelectron Spectroscopy ranks as one of the most important advances in the chemical physics during the past decades. Information derivable from this technique is of vital importance in understanding the electronic structure of atoms, molecules, ions and solid materials. When combined with ab initio or DFT theoretical calculations. Hel photoelectron spectroscopy (PES) can provide rich information on orbital energies, ionic states, bonding and fine vibrational structures for the molecules studied that are not easily provided by other experimental techniques.The PE Spectroscopy is at present the best technique available for obtaining a direct measure of atomic and molecular energy levels. The information derivable from these measurements is greatly enhanced if a theoretical model is available for comparison and discussion of the results. As is well known, molecular orbital theory provides a simple, although reasonable, basis for interpretation of PE spectra. On the other hand, more extended calculations of the energies of the molecular and ionic states involved in the photoelectron transitions provide a unique challenge for quantum chemistry.Quantum chemistry is becoming increasingly important within the field of chemistry. Its steady growth, application, and influence is evidenced by modern chemical attitudes and approaches as well as the continuous increase in the sophistication of computational techniques. Despite this sophistication, exact solutions of the schrodinger equation for many-electron molecules are not available. The best solutions to the schrodinger equation come from experiments; experiments using PE spectroscopy provide direct energy differences between a molecule andspectroscopy provide direct energy differences between a molecule and its molecular ion, thereby providing "exact" solutions of the schrodinger equation for those specific systems.The complementary nature of PE spectroscopic measurements and quantum chemical predictions constitutes a true symbiosis: quantum chemical theories provide necessary models for spectral interpretation, while the spectra serve as both an excellent test for the success of the theories and as a basis for empirical parameterization of the calculations.At the beginning of this thesis, the previous research studies are surveyed. Then the principle and experiment technique of Photoelectron Spectroscopy are covered in Chapter two. We present an introduction to the UPS-Machine-II spectrometer which is built specially for detecting transient species. The improvement in this spectrometer is also referred. In Chapter Three, Modern quantum chemistry theory and electronic structure theory are described briefly. Then the electronic state of a molecule system and calculation methods for ionization potentials, as well as the theory about spin-orbital coupling are also discussed in detail.The main part of the thesis begins with the studies on the halogen azide XN₃ (X=F, Cl. Br, I). The specific geometry optimization on XN₃ and XN₃⁺ is employed on B3LYP/6-311+G(2df). The pure FN3 and IN₃:, beam is generated in situ, and their PE spectra are recorded for the first time. The ionization potentials, the properties of molecular orbitals and other detailed information are also reported. We found the Outer Valence Green's Function (OVGF) calculations can give very good result of ionization potentials. A novel method to generate original species under the condition of the super vacuum and low temperature, i.e. the gas-solid heterogeneous reaction, is described for the first time.In Chapter Five. Electron density analysis on the isomerization reaction between XSCN and XNCS (X=C1. Br) was performed base...