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 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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.002 |
| Meta-epidemiology (broad) | 0.001 | 0.003 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.558 | 0.003 |
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; both teacher heads agree on what is shown here.
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".