Study of Chemistry in Droplets with Net Charge before and after Coulomb Explosion: Ion-Induced Nucleation<i>in Solution</i>and Implications for Ion Production in an Electrospray
Bibliographic record
Abstract
Droplets with net charge are essential intermediaries in the production of gaseous ions in the electrospray (ES) ion source. There could be a wealth of knowledge regarding the chemistry that occurs in such droplets as a result of their violation of electroneutrality. Such information could lead to improved understanding of the ion generation process in an ES along with factors that affect it. The experiments performed involved the levitation of individually charged droplets that were, and were not, allowed to undergo Coulomb explosion while they remained levitated in an electrodynamic balance (EDB). Through examination of precipitates formed within the levitated droplets, it was observed that onset of NaCl precipitation was promoted in droplets (glycerol:water 9:1 v/v) that had mass-to-net-charge (m/z) ratio <-4.8 x 10(9) amu/e. This threshold m/z value is exceeded in essentially all droplets generated in an ES because it is above the calculated threshold for Coulomb explosion. This finding suggests that cluster formation in droplets having net charge could occur at solute concentrations lower than would be anticipated on the basis of homogeneous nucleation. The effect of large entities such as precipitates existing in the droplet on the dynamics of droplet Coulomb explosion was also examined. Using droplets whose initial size and magnitude of net charge were equivalent within experimental error but having different concentration of solutes, we showed that the m/z of their main residues following Coulomb explosion were different. Micrometer-size droplets containing 20 nm fluorescent beads that underwent Coulomb explosion resulted in main residues that had higher m/z for higher initial bead concentration in the starting solution (320 nM) when compared to main residues resultant from starting solutions having lower initial bead concentration (21 nM).
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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 | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".