Studies Of Valence Satellites Of Molecules By High-Resolution Electron Momentum Spectroscopy

This dissertation presents experimental studies of valence satellites of CS₂ and N₂O by high-resolution electron momentum spectroscopy (EMS), as well as theoretical calculations on the ionization spectra of C₂H₆ and CF_nCl_4-n using symmetry adapted cluster- configuration interaction (SAC-CI) method. It comprises six chapters as followings:In Chapter 1, the background, research methods and some recent advancement for the studies of correlation satellites have been introduced.The basic theoretical framework and experimental methods of electron momentum spectroscopy are described briefly in Chapter 2.Chapter 3 introduces the theoretical computational methods employed in this dissertation including Hartree-Fock (HF) theory, density functional theory (DFT) and SAC-CI.The EMS studies on valence satellites of CS₂ are presented in detail in Chapter 4. Taking the advantage of the high energy resolution of 0.54 eV, four main peaks and five satellites in the outer-valence region are resolved. The assignments and pole strengths for these satellite states are achieved by comparing the experimental electron momentum profiles with the corresponding theoretical ones calculated using HF and DFT methods. The results are also compared in detail with the recent SAC-CI general-R calculations. General agreement is satisfactory, while the present experiment suggests cooperative contributions from ²Î _u,²Î£_g⁺ states to satellite 2 and ²Î£_g⁺, ²Î _g states to satellite 3. Besides, relatively low pole strength for X²Î _g state is obtained which contradicts all the theoretical calculations. Chapter 5 introduces the investigation of valence satellites of N₂O using the same high-energy-resolution spectrometer. Four main peaks and six satellites in the outer-valence binding energy spectra are resolved and the corresponding electron momentum profiles are extracted. By directly comparing the experimental momentum profiles with the theoretical ones, the assignments and pole strengths for these satellite states are obtained.Theoretical studies on the ionization spectra of C₂H₆ and CF_nCl_4-n using SAC-CI method have been expatiated in Chapter 6. The SAC-CI general-R method simulates the EMS binding energy spectra quite accurately and the detailed assignments of the satellite peaks are given. The SAC-CI analysis indicates that the unexpected discrepancy between experimental and theoretical electron momentum profiles for 3a1 orbitals of CF_nCl_4-n molecules are due to inner-valence correlation satellites.The summarizations of the dissertation and the prospects are presented in the end of the dissertation.