Study On Spectroscopy Of Rydberg Atoms In Strong External Fields

Study on spectroscopy of Rydberg atoms in strong external fields is one of the most important issues in atomic molecular and optical physics. Atom in external fields is related to many basic theoretical problems in quantum mechanics, and it proves that it is an idea system of studying the quantum-classical correspondence. In addition, the research on atoms in strong fields influence the astrophysics, plasma physics and laser physics directly. In this thesis, we investigate on the external fields effects on the alkali metal atoms theoretically and on alkali earth metal Barium atom experimentally. The main research contents include:(1) We presented a new method to calculate the spectrum of atom in external fields. This method combines the analytical Coulomb potential and the B-spline techniques, which reduces the computing time greatly. This merit benefits from the unique feature of B-Spline basis which keeps the Hamiltonian having a banded structure.(2) Based on our method, we calculate the spectra of several atoms in external fields, which reveals many physical interactions in atoms. The diamagnetic spectra of Rb atom in strong magnetic fields shows the coupling between states with the same parity while the π and a polarized diamagnetic spectra of H and Li atoms reveals the atomic core effect of lithium and the similar characteristics to hydrogen atom at high energy levels. The Stark spectra of Rb atom in strong electric fields shows the coupling between states with the different parity. The levels anti-crossing effect is also discussed. The calculation for π polarized spectra of H, Li and Rb atoms in parallel electric and magnetic field reveals the dependence of diamagnetic spectra on electric field strength. We discuss the three types of states for atoms in parallel fields.(3) Experimentally, we studied the resonance structures of Barium atom above classical ionization threshold, which is in consistent with our theoretical calculation results. We discuss the coupling of discrete and continuum states and its influence on the structure of the spectra. The resonance structure characteristics are analyzed with semi classical theory. In addition, the similar characteristics with hydrogen atom of Barium atom around near-threshold are analyzed.