Nonsequential double ionization of helium in IR+XUV two-color laser fields II: collision-excitation ionization process
Bibliographic record
Abstract
Abstract We recently investigated the collision-ionization mechanism of the nonsequential double-ionization (NSDI) process in IR+XUV two-color laser fields [(2016) Phys. Rev. A 93 043417]. Here, we extend this work to study the collision-excitation-ionization (CEI) mechanism of the NSDI processes in the two-color laser fields with different laser conditions. It is found that the CEI mechanism makes a dominant contribution to the NSDI as the extreme ultraviolet (XUV) photon energy is smaller than the ionization threshold of the He + ion, and the momentum spectrum shows complex interference patterns and symmetrical structures. By channel analysis, we find that, as the energy carried by the recollision electron is not enough to excite the bound electron, the bound electron will absorb XUV photons during their collision; as a result, both forward and backward collisions make a comparable contribution to the NSDI processes. However, it is found that, as the energy carried by the recollision electron is large enough to excite the bound electron, the bound electron does not absorb any XUV photon and it is excited only by sharing the energy carried by the recollision electron, hence the forward collision plays a dominant role in the NSDI processes. Moreover, we find that the interference patterns of the NSDI spectra can be reconstructed by the spectra of two above-threshold ionization (ATI) processes, which may be used to analyze the structure of the two separate ATI spectra by NSDI processes.
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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 | 0.000 | 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) | 0.000 | 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".