Isotopically selective photoionization of calcium atoms

Three-stage selective photoionization of calcium atoms was investigated using cw dye lasers. Selective excitation was due to an intercombination transition 4s^{2 1}S₀→4s4p ³P₁ (λ = 657.3 nm), additional excitation by a transition 4s4p ³P₁→4s5s ³S₁ (λ = 612.2 nm), followed by final ionization at λ = 488.0 nm from an argon laser. The photoion currents of different nuclides were determined using an MKh-7303 mass spectrometer. The ratios of the ion currents were used to find the separation coefficients a which were ~ 900 for ⁴⁸Ca, ~ 1400 for ⁴⁴Ca, and ~ 5500 for ⁴²Ca.