The Structure of the Protonated Adenine Dimer by Infrared Multiple Photon Dissociation Spectroscopy and Electronic Structure Calculations
Bibliographic record
Abstract
The infrared multiple photon dissociation (IRMPD) spectrum of electrosprayed adenine proton-bound dimers were recorded in the gas-phase inside the cell of a Fourier transform ion cyclotron resonance spectrometer coupled to a tunable optical parametric oscillator/amplifier infrared laser. While gas-phase B3LYP/6-31+G(d,p) calculations indicate that the four lowest isomers are essentially isoenergetic, comparisons of the experimental and predicted IR spectra suggest that only two of the four isomers are observed in the experiment. However, computed solvation effects, as modeled using both a polarizable continuum model and microsolvation with five explicit water molecules, preferentially stabilize these two observed isomers, consistent with the interpretation of the IRMPD spectra. This work shows that for these small species the solvent-phase structure is preserved. It also demonstrates the potential danger of using gas-phase calculations to predict the structures of gaseous ions born in solution, such as those from an electrospray source.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".