Isotope selective near-resonant two-photon ionization of ~(41)Ca isotope via the 4s11s ~(1)S_(0) intermediate state

摘要

Isotope selective excitation of a ~(41)Ca isotope using a near-resonant two-photon ionization scheme 4s~(2) ~(1)S_(0) -> ~(422.7924 nm, 413.3685 nm) 4s11s ~(1)S_(0) -> ~(514.5 nm) Ca~(+) has been proposed for using the ~(41)Ca isotope in applications as a tracer in biomedical studies. The ionization efficiency and optical selectivity have been calculated for various powers of the excitation and ionization laser. Under the optimized excitation and ionization laser powers the ionization efficiency for the studied scheme is found to be 1.7 X 10~(-4). The optical selectivity value is approx1.0 X 10~(5) and both of these values are either comparable or slightly better than the earlier published work by our group. The overall ionization efficiency for the two-photon ionization scheme considering the throughput factor is 5 X 10~(-3), which is 2 orders of magnitude higher than the stepwise excitation process. Therefore, the higher ionization efficiency of the process enables monitoring of the tracer isotope for longer durations. In combination with a mass spectrometer, an abundance sensitivity of approx10~(10) can be obtained, which is adequate for biomedical applications.