Photodissociation Dynamics of H <sub>2</sub> S via the 3 <sup>1</sup> <i>A</i> ′ State: Dominance of Dual Intersection-Induced Barriers
Bibliographic record
Abstract
Hydrogen sulfide (H 2 S), a major sulfur carrier in the interstellar medium, undergoes ultraviolet photodissociation that shapes interstellar sulfur chemistry and sulfur isotope fractionation. Here we construct a four-state diabatic potential energy matrix for the lowest four 1 A ′ states of H 2 S using high-level ab initio data and a neural-network-based diabatization scheme. Quantum wave packet dynamics on the 3 1 A ′ state reproduce the main experimental features of the H + SH(X 2 Π/A 2 Σ + ) internal energy distributions at 143.15 nm, with minor discrepancies likely due to the unaccounted contributions of 1 A ″ states. Trajectory surface-hopping simulations show that H 2 S undergoes transient trapping in a basin formed by dual intersection-induced barriers on the 2 1 A ′ surface. This dual-barrier topology restricts dissociation to a narrow escape pathway along the bond-angle coordinate, promoting SH(A 2 Σ + ) formation. The results reveal a new mechanism in which dual intersection-induced barriers govern product branching in high-lying electronic states.
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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".