Origin of C(1s) binding energy shifts in amorphous carbon materials
Bibliographic record
Abstract
The quantitative evaluation of the carbon hybridization state by x-ray photoelectron spectroscopy (XPS) has been a surface-analysis problem for the last three decades due to the challenges associated with the unambiguous identification of the characteristic binding energy values for <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:msup> <a:mrow> <a:mi>sp</a:mi> </a:mrow> <a:mn>2</a:mn> </a:msup> </a:math> - and <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:msup> <b:mrow> <b:mi>sp</b:mi> </b:mrow> <b:mn>3</b:mn> </b:msup> </b:math> -bonded carbon. Here, we computed the binding energy values of C(1s) core electrons on the absolute energy scale for model structures of amorphous carbon (a-C) using density functional theory (DFT). The DFT calculations show that in the case of hydrogen-free a-C, the C(1s) binding energy for <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:msup> <c:mrow> <c:mi>sp</c:mi> </c:mrow> <c:mn>3</c:mn> </c:msup> </c:math> carbon atoms is a distribution found approximately 1 eV higher than the binding energy distribution of <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:msup> <d:mrow> <d:mi>sp</d:mi> </d:mrow> <d:mn>2</d:mn> </d:msup> </d:math> -hybridized carbons. However, the introduction of hydrogen in the a-C network reduces the distance between the characteristic signals of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"> <e:msup> <e:mrow> <e:mi>sp</e:mi> </e:mrow> <e:mn>3</e:mn> </e:msup> </e:math> - and <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"> <f:msup> <f:mrow> <f:mi>sp</f:mi> </f:mrow> <f:mn>2</f:mn> </f:msup> </f:math> -bonded carbon due to the increased ability to screen the core hole by neighboring hydrogen atoms as compared to carbon atoms. This effect hinders the unambiguous quantification of the carbon hybridization state on the basis of C(1s) XPS data alone. This work can assist surface scientists in the use of XPS for the accurate characterization of carbon-based materials.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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 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".