Boiling of catechol secondary organic aerosol when heated to mild temperatures (36-52 °C) due to acetone and carbon dioxide formation and high viscosity
Bibliographic record
Abstract
Thermal desorption measurements, including thermal desorption mass spectrometry, are often used to determine the volatility and chemical composition of secondary organic aerosol (SOA). Accurately interpreting such measurements requires understanding the response of SOA to heat. Using optical microscopy, we monitored catechol + O₃ SOA during heating at mild temperatures (36-52 °C). Catechol + O₃ SOA is a type of SOA formed in wildfire plumes. Surprisingly, the SOA particles appeared to boil when heated to these temperatures. We identified acetone and CO₂ as dominant species emitted from the SOA during heating, implying decomposition of the SOA components. Using mass spectrometry techniques, we observed catechol dimers to be the major product in unheated SOA and observed the degradation of these dimers after heating. Viscosity calculations suggested the mixing time of acetone and CO₂ within the particles was 11 h and 1 h at temperatures of 36 and 52 °C, respectively. The observed boiling can be explained by the production and slow mixing of acetone and CO₂ within the SOA particles when subjected to mild temperatures. Our results underscore the importance of considering decomposition, high viscosities, and slow mixing times when interpreting thermal desorption measurements of SOA, even when heating to mild temperatures.
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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 | 0.000 |
| 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 | 0.001 |
| 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".