A new apparatus for gas-phase low temperature kinetics study: Kinetics measurement and product detection of the CH + propene reaction at 23 K
Bibliographic record
Abstract
We have developed a novel instrument to study reaction kinetics of astrochemical interest at low temperatures. This setup integrates laser-induced fluorescence (LIF) and vacuum ultraviolet (VUV) photoionization reflectron time-of-flight mass spectrometry (ReTOFMS) with a supersonic uniform low-temperature flow. A pulsed helium Laval nozzle with a Mach number of 6 was employed, achieving a temperature of 23 ± 3 K and a density of (2.0 ± 0.4) × 1016 molecule cm-3. The second-order rate coefficient for the reaction between the methylidyne radical (CH) and propene (C3H6) at 23(3) K was determined to be (3.4 ± 0.6) × 10-10 cm3 molecule-1 s-1 using LIF kinetics measurements. VUV (118.27 nm) photoionization ReTOFMS detected a dominant product channel, CH + C3H6 → C4H6 + H, without isomer identification. Another less intense mass peak at m/z 53 was also observed, which could either result from the dissociative ionization of the energized C4H6 primary products or indicate another product channel, C4H5 + H2. Given the presence of CH and C3H6 in cold molecular clouds (e.g., TMC-1, Lupus-1a, L1495B, L1521F, and Serpens South 1a), it is predicted that these products can exist in low-temperature interstellar environments.
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 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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".