Microscale Simultaneous Measurement of Carbon and Nitrogen Isotopes on Natural Diamond
Bibliographic record
Abstract
Simultaneous analysis of carbon and nitrogen isotope ratios by SIMS was applied for the first‐time to a natural diamond from the Kelsey Lake kimberlite, State Line Distinct, Colorado (UWD‐1). This in situ procedure is faster, reduces sample size for analysis, and measures both isotope ratios from a single ~ 10 μm diameter pit, a critical advantage for zoned diamonds. The carbon isotope ratio (expressed as δ 13 C VPDB ) of the bulk UWD‐1 crystal, determined by the conventional combustion method in the present study, is ‐5.9‰ ± 0.2‰ (VPDB, 2 s ). Nitrogen mass fraction ([N]) and isotope ratio (expressed as δ 15 N Air ) were determined by stepwise combustion and gas‐source mass‐spectrometry, resulting in 553 ± 64 μg g ‐1 and ‐6.7‰ ± 1.1‰ (Air, 2 s ), respectively. Secondary ions of 12 C 2 ‐ , 12 C 13 C ‐ , 12 C 14 N ‐ , and 12 C 15 N ‐ were simultaneously measured by SIMS using three Faraday cups and one electron multiplier. The spot‐to‐spot reproducibility of δ 13 C and δ 15 N values for the UWD‐1 (178 spots on sixteen chips, 10 μm spots), were 0.3‰ and 1.6‰, respectively (2 s ). While 12 C 14 N ‐ / 12 C 2 ‐ ratios, which are an indicator for [N], varied up to 12% among these sixteen chips, such variation did not correlate with either δ 13 C or δ 15 N values. We propose that UWD‐1 is a suitable reference sample for microscale in situ analysis of δ 13 C and δ 15 N values in diamond samples.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".