Determination of a three-step excitation and ionization scheme for resonance ionization and ultratrace analysis of Np-237

作者：Raeder S^*; Stoebener N; Gottwald T; Passler G; Reich T; Trautmann N; Wendt K

来源：Spectrochimica Acta Part B: Atomic Spectroscopy , 2011, 66(3-4): 242-247.

DOI：10.1016/j.sab.2011.02.002

• Neptunium
• Resonance ionization spectroscopy
• RIMS

The long-lived radio isotope (237)Np is generated within the nuclear fuel cycle and represents a major hazard in the final disposal of nuclear waste. Related geochemical research requires sensitive methods for the detection of ultratrace amounts of neptunium in environmental samples. Resonance ionization mass spectrometry (RIMS) has proven to be one of the most sensitive methods for the detection of plutonium. A precondition for the application of RIMS to ultratrace analysis of neptunium is the knowledge of an efficient and selective scheme for optical excitation and ionization. Therefore, a multitude of medium to high-lying atomic levels in neptunium was located by applying in-source resonance ionization spectroscopy. By using excitation via six previously known first excited, intermediate levels of odd parity, a set of twelve so far unknown high-lying levels of even parity were identified and studied further for their suitability in resonant excitation/ionization schemes. Autoionizing resonances for efficient ionization of neptunium atoms were subsequently accessed spectroscopically. Altogether five resonance ionization schemes were investigated and characterized concerning their saturation behavior and relative efficiency. Applying a calibrated sample, an overall efficiency of 0.3% was determined.

• 出版日期2011-4