Lifetimes of Fine Levels of Li Atom for 20 < n < 31 by Extended Ritz Formula

Lithium and lithium-like elements look like hydrogen atoms if their two electrons and the nucleus are considered a core around which a single electron is orbiting. The energy and radii expressions for hydrogen atoms can be used for lithium and lithium-like elements; an important modification is introducing an effective principal quantum number. The effective principal quantum number differs from the principal quantum number of hydrogen by the quantum defect. Quantum defect has respective values for various levels of lithium and lithium ions. In this study, we used extended Ritz formulas to calculate quantum defects required to calculate energies of ns, np, nd, and nf series. Using these energies, we calculated transition probabilities and then the lifetimes of the lithium levels. The lifetimes were calculated with the published data; an excellent agreement was recorded. The work also extended the available list of lifetimes. Forty lifetimes are new and presented for the first time. a polynomial for each of the ns, np, nd, and nf series lifetimes has been produced that fits well the lifetime values