Observation of High-lying Odd Levels of Uranium Atom in Two-colour Three-photon Resonant Photoionization Spectrum

1 Introduction Thousands of energy levels of uranium atom are being found, but it is difficult to identify and assign them because of the complicatedness of UI spectrum. Most of the information about the uranium atom energy levels was obtained from the analysis of the emission or absorption spectra got in conventional sources, such as hollow cathode or electrodeless discharge lamps. As higher excited states are thinly populated in these conventional sources, most of the data available in literature pertain to low and medium energy