Incorporation of Thermal Rotation of Drifting Ions into Mobility Calculations: Drastic Effect for Heavier Buffer Gases
Bibliographic record
Abstract
Ion mobility spectrometry (IMS) assumes increasing prominence among the tools for characterization of gas-phase ions and analysis of complex mixtures. The assignment of features observed in IMS experiments to specific structures necessitates the calculation of mobilities for plausible candidate geometries. All previous methods for these calculations have assumed that the ion−buffer gas collisions are fully elastic and that the drifting ions cannot rotate during a collisional event. This paradigm does not mesh well with the fact that the measured quantity is the orientationally averaged collision integral. Here we model the effect of the thermal rotation of drifting ions on their mobility. Simulations show that the cross sections for rotating objects are greater than those for static ones because a molecular image “blurs out” over the duration of collision. This increase is particularly significant for light and elongated ions. For a given ion, the effect is dramatically larger in heavy buffer gases, in some cases exceeding 20%. Present findings reveal the importance of accounting for the nonelasticity of scattering in ion mobility calculations.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".