Numerical studies on the isotopic selective photoionization of ytterbium in a three-step ionization scheme

Abstract

Abstract Numerical studies of selective photoionization of ytterbium isotope have been carried out based on a three-step photoionization scheme, 4f 146s 2 1S0 (0 cm-1) → 4f 146s6p 3P1 (17992.008 cm-1) → (4f 136s 26p) (7/2, 3/2)2 (35196.98 cm-1) → auto-ionization state (52353 cm-1) → Yb+, by the density matrix theory with the consideration of atomic hyperfine structures and magnetic sublevels. To examine the physical model, the numerical isotopic abundances of ytterbium are compared with those of mass spectroscopy experiments and good agreements are acquired. The excitation and ionization processes of ytterbium are discussed and analyzed in detail on this basis, especially for odd isotopes. The effects of frequency detuning, power densities, spectral bandwidths, polarization of two excitation lasers and atomic Doppler broadening on the total ionization yield and isotopic abundance are presented numerically and the optimization excitation conditions for 176Yb enrichment are identified semi-quantitatively.