Isotope selective near-resonant two-photon ionization of 41Ca isotope via the 4s11s 1S0 intermediate state

Isotope selective excitation of a 41Ca isotope using a near-resonant two-photon ionization scheme 4s2 1S0-->422.7924 nm,413.3685 nm4s11s 1S0-->514.5 nmCa+ has been proposed for using the 41Ca 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 1.7x10(-4). The optical selectivity value is approximately 1.0x10(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 5x10(-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 approximately 10(10) can be obtained, which is adequate for biomedical applications.