1280-Fe

2022-03-30

Kita2010

1. Primary ions: Duoplasmatron source, O-, -13 kV, 7nA, 25 μm

2. Secondary Fe+ ions: +10kV accelerate

3. Transfer lens optics: tuned at magnifications of 200

        Contrast aperture: 400 μm diameter 

        Entrance slit: 120 μm width

        Field aperture: 6000×6000 μm² 

        Energy slit: 40 eV width for low energy ions

        Exit slit: 400μm

    Sec ions transmission:  ~

    X-Y mode for secondary optics

5. 53Cr+ was monitored with EM: very low level, no significant 54Cr 

6. Analysis time: ~4 mins

        Presputtering: 60 s

        Automatic centering: 90 s

        Integration signals: 4 s × 20 cycles

7. Internal and external precisions for 56Fe/54Fe: 0.1-0.2‰

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Heterogeneity monitor: 0.6 ‰ in δ56Fe

Ion yield variability (positive correlation with δ56Fe): maybe a result of an instrumental bias changing with  crystal orientation

Ion channeling: inoization efficiency of Fe+ varies with oxidized conditions (eg., using O2- primary ions) → positive? → IMF favors heavy isotope

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NOTES

1. Heterogeneity measurement;

2. Ion yield variability;

3. Secondary ions transmission efficiency