Quantifying absolute carbon isotope ratios by AMS

Vogel, John S.; Giacomo, Jason; Dueker, Stephen R.

doi:10.1016/j.nimb.2012.03.033

Cited by 3 publications

(2 citation statements)

References 47 publications

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“…However, surface effects ionize less than 3% of these sputtered atoms (Litherland et al 1987). Creation of elemental anions through ion-pair production (IPP) during collisions of neutral sputtered products with neutral gaseous cesium (Cs) in ground or excited states is suggested to be much more efficient than surface ionization for Cs sputter ion sources (Vogel 2013(Vogel , 2015(Vogel , 2016(Vogel , 2018Vogel et al 2013). Sputtered atoms come off a surface with a energy distribution maximizing at half their binding energy (BE) (Sigmund 1969).…”

Section: Introductionmentioning

confidence: 99%

Ion-pair Ionization in CO₂-fed Cesium Sputter Sources

Vogel¹,

Stolz

2019

Radiocarbon

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A collision-radiation model of the solid sample cesium sputter ion source led to the rediscovery of anion production by ion-pair production. The model revealed physical processes that may produce high current outputs from such sources and suggested new ways of obtaining high outputs at lower heat and conductive stress to the source. Primary among these solutions is the electron excitation of primary Cs0 recycled from the sample to provide states that efficiently create chosen anions. Here we look at how the processes might apply to gas-fed ion sources.

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Section: Introductionmentioning

confidence: 99%

Ion-pair Ionization in CO₂-fed Cesium Sputter Sources

Vogel¹,

Stolz

2019

Radiocarbon

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“…I was prompted to understand the observed plasma after finding that an AMS was capable of measuring accurate absolute isotope ratios over long periods of time [13]. This result required that the ion source provide beams of isotopes without dependence on the isotopic mass and variations in sample surfaces.…”

Section: Introductionmentioning

confidence: 99%

Anion formation by neutral resonant ionization

Vogel¹

2015

Nuclear Instruments and Methods in Physics Research Section B:

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Increased ¹⁴C AMS Efficiency from Reduced Competitive Ionization

Vogel¹,

Giacomo

2016

Radiocarbon

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Observation 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.

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Quantifying absolute carbon isotope ratios by AMS

Cited by 3 publications

References 47 publications

Ion-pair Ionization in CO₂-fed Cesium Sputter Sources

Ion-pair Ionization in CO₂-fed Cesium Sputter Sources

Anion formation by neutral resonant ionization

Increased ¹⁴C AMS Efficiency from Reduced Competitive Ionization

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Quantifying absolute carbon isotope ratios by AMS

Cited by 3 publications

References 47 publications

Ion-pair Ionization in CO2-fed Cesium Sputter Sources

Ion-pair Ionization in CO2-fed Cesium Sputter Sources

Anion formation by neutral resonant ionization

Increased 14C AMS Efficiency from Reduced Competitive Ionization

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Product

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About

Ion-pair Ionization in CO₂-fed Cesium Sputter Sources

Ion-pair Ionization in CO₂-fed Cesium Sputter Sources

Increased ¹⁴C AMS Efficiency from Reduced Competitive Ionization