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Optimizing the analyte introduction for 14C laser ablation-AMSElectronic supplementary information (ESI) available. See DOI: 10.1039/c7ja00118e
Erscheinungsjahr
2017-08
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Recently a novel approach enabling spatially resolved analyses of radiocarbon (
14
C) in carbonates has been introduced, combining laser ablation with accelerator mass spectrometry (LA-AMS). Here, we present a comprehensive study to find optimum working conditions for LA-AMS. The stepwise optimization and characterization process comprises (i) finding a suitable laser source for the ablation of carbonates with highest CaCO
3
to C
gas
(
i.e.
CO
2
or CO) conversion rate, (ii) studying different capillaries with different gas flow resistance that interface the LA-cell with the ion source of the AMS system, and (iii) determining the exchange rate of the LA cell and the width of a stalagmite's growth stop under real measurement conditions. Three laser sources (Nd:YAG@266 nm; Nd:YAG@213 nm; ArF excimer@193 nm) were tested at different fluences (3 and 23 J cm
−2
) for their C
gas
-conversion efficiencies. Highest C
gas
-conversion efficiencies of (70 ± 4)% were found with an ArF excimer laser, independently of laser fluence. The characterization of the system using different capillaries showed that gas flow rates applied in LA-AMS are more than a factor of five higher than for regular
14
C AMS gas measurements, which probably results in reduced ionization efficiencies of the LA-AMS setup. An exchange rate of 10 min
−1
is determined for the LA-cell design applied in this study by matching a
14
C dataset derived by LA-AMS with modeled data (
χ
2
-fit). Additionally, the model allowed to estimate the width of a growth stop in a stalagmite sample to be on the order of 0.25 mm.
Sample introduction of online radiocarbon (
14
C) analysis using LA coupled to accelerator mass spectrometry (AMS) has been characterized and optimized.
Sprache
Englisch
Identifikatoren
ISSN: 0267-9477
eISSN: 1364-5544
DOI: 10.1039/c7ja00118e
Titel-ID: cdi_rsc_primary_c7ja00118e
Format
–
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