High-resolution photoelectron and photoion spectroscopic studies of ammonia using two-color infrared-vacuum ultraviolet laser systems

Two-color two-photon IR-VUV PFI-PE and PIE detection schemes using IR-OPO/OPA laser and coherent VUV laser systems have been demonstrated to provide high-resolution photoelectron and photoion spectra of polyatomic molecules. Two-color IR-VUV PFI-PE and PIE spectra are obtained by preparing molecules in selected rovibrational states by IR excitation prior to VUV photoionization. The resultant PFI-PE and PIE spectra are tremendously simplified, allowing us to resolve the rotational structures of photoelectron spectra of polyatomic molecules and to study state-to-state and state-selected photoionization dynamics of simple polyatomic molecules. First, two-color two-photon IR-VUV-PFI-PE method has been employed to provide completely rotationally resolved, i.e., both J-state and K-state resolved rovibronic spectra of small molecules such as ammonia. The K-state resolution of rotational structure helps to understand the photoionization dynamics by enabling the determination of the parity of the photoelectron partial wave. The extended BOS simulations are used to help interpret rotationally resolved photoelectron spectra of symmetric tops such as ammonia. Second, two-color two-photon IR-VUV photoion depletion (PID) spectroscopy has been introduced for the first time, which can be considered as a variant of IR-UV pump probe methods. The two-color IR-VUV-PID scheme has been demonstrated as a valuable method for determining the rotational character of autoionizing Rydberg resonances observed in single-photon VUV-PIE studies. This dissertation shows the application of the IR-VUV studies to ammonia. In addition, synchrotron based PFI-PE study of ammonia has been performed to provide a grand view of photoionization dynamics of ammonia.