Atomic Trajectories of a Bimolecular Reaction Visualized by Ultrafast Electron Diffraction
Bibliographic record
Abstract
Bimolecular reactions are ubiquitous in chemistry, but it is exceptionally difficult to resolve the motion of atoms for such processes on the ultrafast timescales that the breaking and creation of chemical bonds occur. Detecting small changes in atom positions requires high temporal and spatial resolution and reliable signal-to-noise characteristics. Here, we have exploited solid-state alignment to track a photoinduced bimolecular disproportionation reaction that transforms two pairs of adjacent triiodide anions into the metastable tetraiodide molecule and the diiodide fragment. We use ultrafast electron diffraction and dynamic structure refinement, where the atomic displacements are directly reconstructed from the diffraction data with plausible restraints on the atomic trajectories starting from the known ground-state structure. The excited-state structures are supported by theoretical calculations in the solid state and the reaction courses show clear site dependence on the ultrafast timescale. Our results provide a close-up view of the atomic motions involved in this classic reaction in real time, from bond elongation to breaking at the parent ion, to collision and subsequent bond formation of the liberated I atom with the neighbouring triiodide, all within a picosecond.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| 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".