München 2004 – scientific programme
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A: Atomphysik
A 12: Atomspektroskopie II
A 12.3: Talk
Tuesday, March 23, 2004, 17:00–17:15, HS 133
Efficient three-step, two-color ionization of plutonium using a resonance enhanced 2-photon transition into an autoionizing state — •P. Kunz1, G. Huber1, G. Passler1, and N. Trautmann2 — 1Institut für Physik, Universität Mainz, 55099 Mainz, Germany — 2Institut für Kernchemie, Universität Mainz, 55099 Mainz, Germany
Resonance ionization mass spectrometry (RIMS) is a well established method for isotope selective ultra-trace analysis of long-lived radioisotopes. For plutonium a three-step, three-color laser excitation scheme has been applied for efficient element- as well as isotope-selective ionization. Thus, detection limits of 106 to 107 atoms have been achieved for various types of environmental and biological samples. We present an alternative three-step, two-color ionization scheme including a two-photon transition from an excited state into a high-lying autoionizing state, yielding a similar overall efficiency as the three-step, three-color scheme. In this way, only two tunable lasers are needed, while the benefits of the three-color excitation (high selectivity, good efficiency and low non-resonant background) are preserved or even improved. The two-photon transition has been characterized with respect to saturation behavior and line width. The resonance enhancement effect of intermediate bound states will be discussed.