Electron Induced Surface Reactions of HFeCo<sub>3</sub>(CO)<sub>12</sub>, a Bimetallic Precursor for Focused Electron Beam Induced Deposition (FEBID)
Bibliographic record
Abstract
The use of bimetallic precursors in focused electron beam induced deposition (FEBID) allows mixed metal nanostructures with well-defined metal ratios to be generated in a single step process. HFeCo 3 (CO) 12 is an example of one such bimetallic precursor that has previously been shown to form deposits with unusually high metal content (>80%) as compared to that of typical FEBID deposits (<30% metal content). To better understand the elementary bond breaking steps involved in FEBID of HFeCo 3 (CO) 12, we have employed a UHV surface science approach to study the effect of electron irradiation on nanometer thick films of HFeCo 3 (CO) 12 molecules. Using a combination of in situ X-ray photoelectron spectroscopy and mass spectrometry, we observed that the initial step of electron induced HFeCo 3 (CO) 12 dissociation is accompanied by desorption of ∼75% of the CO ligands from the precursor. A comparison with recent gas phase studies of HFeCo 3 (CO) 12 indicates that this process is consistent with a dissociative ionization process, mediated by the secondary electrons produced by interaction of the primary beam with the substrate. The loss of CO ligands from HFeCo 3 (CO) 12 in the initial dissociation step creates partially decarbonylated intermediates, HFeCo 3 (CO) x ( x avg. ≈ 3). During a typical FEBID process, further electron exposure or thermal reactions can further transform these intermediates. In our UHV surface science approach, the effect of these two processes can be studied in isolation and identified. Under the influence of further electron irradiation, XPS data reveals that the remaining CO ligands in the partially decarbonylated intermediates decompose to form residual carbon and iron oxides, suggesting that those CO ligands that desorbed in the initial step are lost predominantly from the Co atoms. However, annealing experiments demonstrate that CO ligands in the partially decarbonylated intermediates desorb under vacuum conditions at room temperature, leaving behind films that are free of almost any carbon or oxygen contaminants. This combination of efficient CO desorption during the initial dissociation step, followed by thermal CO desorption from the partially decarbonylated HFeCo 3 (CO) x ( x avg. ≈ 3) intermediates provide a rationale for the high metal contents observed in FEBID nanostructures created from HFeCo 3 (CO) 12 .
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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 | 0.000 |
| 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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".