Mechanism of enhanced ionization of linear<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msubsup><mml:mrow><mml:mi mathvariant="normal">H</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math>in intense laser fields
Bibliographic record
Abstract
We investigate the mechanism of enhanced ionization that occurs at a critical internuclear distance ${R}_{c}$ in the two-electron symmetric linear triatomic molecule ${\mathrm{H}}_{3}^{+}$ subjected to an ultrashort, intense laser pulse by solving exactly the time-dependent Schr\"odinger equation for a one-dimensional model of ${\mathrm{H}}_{3}^{+}.$ Results of the simulations are analyzed by using three essential adiabatic field states |1〉, |2〉, and |3〉 that are adiabatically connected with the lowest three electronic states ${X}^{1}{\ensuremath{\Sigma}}_{g}^{+},$ ${B}^{1}{\ensuremath{\Sigma}}_{u}^{+},$ and ${E}^{1}{\ensuremath{\Sigma}}_{g}^{+}$ of the field free ion. We give also a simple MO (molecular orbital) picture in terms of these three states to illustrate the important electronic configurations in an intense field. The states |1〉, |2〉, and |3〉 are shown to be composed mainly of the configurations ${\mathrm{HHH}}^{+},$ ${\mathrm{HH}}^{+}\mathrm{H},$ and ${\mathrm{H}}^{+}\mathrm{HH},$ respectively in the presence of the field. We conclude that the overall level dynamics is governed mainly by transitions at the zero-field energy quasicrossings of these three states. The response of ${\mathrm{H}}_{3}^{+}$ to a laser field can be classified into two regimes. In the adiabatic regime $(R<{R}_{c}),$ the electron transfers from one end of the molecule to the other end every half optical cycle thus creating the ionic component ${\mathrm{H}}^{+}{\mathrm{H}}^{+}{\mathrm{H}}^{\mathrm{\ensuremath{-}}}.$ In the diabatic regime $(R>{R}_{c}),$ internuclear electron transfer is suppressed due to electron repulsion and laser induced localization. In the intermediate $(R\ensuremath{\simeq}{R}_{c})$ region, where enhanced ionization occurs, the state |3〉 is most efficiently created by the field-induced nonadiabatic transitions between the states at quasicrossing points. The ``quasistatic'' laser-induced potential barriers are low enough for the electron to tunnel from the ascending (upper) well, thus confirming the quasistatic model at high intensities. Analytic expressions for the critical distance ${R}_{c}$ are obtained from this model and collective electron motion is inferred from the detailed time-dependent two-electron distributions.
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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 | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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".