Charge Resonance Enhanced Ionization of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>CO</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>Probed by Laser Coulomb Explosion Imaging
Bibliographic record
Abstract
The process by which a molecule in an intense laser field ionizes more efficiently as its bond length increases towards a critical distance ${R}_{c}$ is known as charge resonance enhanced ionization (CREI). We make a series of measurements of this process for ${\mathrm{CO}}_{2}$, by varying pulse duration from 7 to 200 fs, in order to identify the charge states and time scales involved. We find that for the $4+$ and higher charge states, 100 fs is the time scale required to reach the critical geometry $⟨{R}_{\mathrm{CO}}⟩\ensuremath{\approx}2.1\text{ }\text{ }\AA{}$ and $⟨{\ensuremath{\theta}}_{\mathrm{OCO}}⟩\ensuremath{\approx}163\ifmmode^\circ\else\textdegree\fi{}$ (equilibrium ${\mathrm{CO}}_{2}$ geometry is $⟨{R}_{\mathrm{CO}}⟩\ensuremath{\approx}1.16\text{ }\text{ }\AA{}$ and $⟨{\ensuremath{\theta}}_{\mathrm{OCO}}⟩\ensuremath{\approx}172\ifmmode^\circ\else\textdegree\fi{}$). The $\mathrm{CO}_{2}{}^{3+}$ molecule, however, appears always to begin dissociation from closer than 1.7 \AA{} indicating that dynamics on charge states lower than $3+$ is not sufficient to initiate CREI. Finally, we make quantum ab initio calculations of ionization rates for ${\mathrm{CO}}_{2}$ and identify the electronic states responsible for CREI.
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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 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.011 | 0.001 |
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".