Theoretical Studies of the Erosion of (100) and (111) Diamond Surfaces by Hyperthermal O(<sup>3</sup>P)
Bibliographic record
Abstract
Direct dynamics simulations, based on density functional-based tight-binding theory with self-consistent charges and also on density functional theory, were used to investigate hyperthermal O( 3 P) atom collisions with (111) and (100) diamond surfaces. Surface functionalizations produced initially, shortly after the start of oxygen-atom exposure, and during steady-state conditions were investigated. Hydrogen atoms are removed from both surfaces by the incoming oxygen atoms, leading to hydroxyl radicals and water molecules. Both surfaces can be damaged by the incoming oxygen during the initial stages of exposure, resulting in the removal of carbon as CO 2 molecules, and functionization of the surfaces with oxygen. The (111) surface is dominated by oxy radicals during steady-state exposure and also has a significant number of carbon atoms with dangling bonds. The (100) surface becomes nearly completely covered by ketone and ether functional groups. Its (2 × 1) reconstruction is opened in the process. Once covered, the (100) surface resists further erosion, presumably because the ether and ketone groups make the surface carbon atoms unattractive to incoming O atoms which act as electrophiles. Two mechanisms exist for the removal of carbon atoms from the (111) surface. The surface can become graphitized by incoming O atom impacts, and graphite is quickly eroded by hyperthermal O atoms. It can also be directly converted to CO 2 as a β-scission-like process makes carbon atoms adjacent to oxy radicals susceptible to electrophilic attack.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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 source (direct Gemma or distilled Codex), 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".