Non-Born-Oppenheimer electronic wave packet in molecular nitrogen at 14 eV probed by time-resolved photoelectron spectroscopy
Bibliographic record
Abstract
We report the observation of a $4.1\phantom{\rule{0.16em}{0ex}}\ifmmode\pm\else\textpm\fi{}\phantom{\rule{0.16em}{0ex}}0.2$ THz quantum beat in the photoelectron spectrum of molecular nitrogen following coherent optical excitation by 14 eV photons and probed by two photons at 800 nm. The intermediate states in the two pathway interference are the valence state ${b}^{\ensuremath{'}}\phantom{\rule{4pt}{0ex}}^{1}\mathrm{\ensuremath{\Sigma}}_{u}^{+}\phantom{\rule{0.16em}{0ex}}v=13$ and Rydberg state ${c}_{4}^{\ensuremath{'}}\phantom{\rule{4pt}{0ex}}^{1}\mathrm{\ensuremath{\Sigma}}_{u}^{+}\phantom{\rule{0.16em}{0ex}}v=4$. The amplitude of the coherent oscillations decays in about 3 ps and does not revive. Opposite phases in the photoelectron yield corresponding to different vibrational levels of the final cationic states $X^{2}\mathrm{\ensuremath{\Sigma}}_{g}^{+}\phantom{\rule{0.16em}{0ex}}v=0,\phantom{\rule{4pt}{0ex}}A{\phantom{\rule{0.16em}{0ex}}}^{2}{\mathrm{\ensuremath{\Pi}}}_{u}\phantom{\rule{0.16em}{0ex}}v=1$, and $X^{2}\phantom{\rule{0.16em}{0ex}}\mathrm{\ensuremath{\Sigma}}_{g}^{+}\phantom{\rule{0.16em}{0ex}}v=\phantom{\rule{0.16em}{0ex}}2,3,4$ are reported. Simulation results show that the interference originates from the strongly mixed character of the two simultaneously excited eigenstates, causing large population oscillations in the zeroth-order Born-Oppenheimer diabatic basis. No quantum beat was observed when probing with single photon at 400 nm, suggesting a resonance with a state just below the ionization potential which acts as a filter, improving the quantum beat contrast.
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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 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".