Author:
Vogel John S,Giacomo Jason A
Abstract
AbstractObservation of 80 µA/mm2 C– current from a 0.5-mm-diameter sample compared to 20 µA/mm2 from a 1-mm-diameter sample contradicts the long-held surface ionization hypothesis of cesium sputter ion source operation. Resonant ionization occurs in neutral Cs plasma above a sample in a sputtered pit or well. A collision-radiation model of that plasma followed electronic excitation and radiation relaxation up to the Cs(7d) state. The Cs(5d) metastable state dominates plasma in a 1-mm-diameter well, but high electron densities in narrow wells drive a majority to Cs(7d) and higher. Competitive ionization by Al2 dimers from the sample holder reduces Cs(7s,p) states resonant in ionization energy with C–. Al anions from states above Cs(7p) in narrow wells also diminish radiation cascades to the Cs(7s,p), reducing C–. We tested sample wells of non-ionizing Zn to maintain high ionization efficiency for small samples in narrow wells.
Publisher
Cambridge University Press (CUP)
Subject
General Earth and Planetary Sciences,Archaeology
Cited by
6 articles.
订阅此论文施引文献
订阅此论文施引文献，注册后可以免费订阅5篇论文的施引文献，订阅后可以查看论文全部施引文献
1. Monoisotopic targets production from atomic and molecular positive ion implantation in a tandem accelerator at low energies;Journal of Physics: Conference Series;2023-10-01
2. Pulsed operation of a SNICS ion source – ionization efficiency and ion current output;Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms;2022-09
3. Ion-pair Ionization in CO2-fed Cesium Sputter Sources;Radiocarbon;2019-12
4. LASIS: The laser assisted sputter ion source;Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms;2019-01
5. Improvements in the measurement of small 14CO2 samples at CologneAMS;Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms;2019-01