State-selective photodissociation dynamics of formaldehyde: Near threshold studies of the H+HCO product channel
Bibliographic record
Abstract
The laser-induced photodissociation of formaldehyde in the wavelength range 309<lambda<330 nm has been investigated using H (Rydberg) atom photofragment translational spectroscopy. Photolysis wavelengths corresponding to specific rovibronic transitions in the A (1)A2<--X (1)A1 2(0)(1)4(0)(3), 2(0)(2)4(0)(1), 2(0)(2)4(0)(3), 2(0)(3)4(0)(1), and 2(0)(1)5(0)(1) bands of H(2)CO were studied. The total kinetic energy release spectra so derived can be used to determine partial rotational state population distributions of the HCO cofragment. HCO product state distributions have been derived following the population of various different N(Ka) levels in the A (1)A2 2(2)4(3) and 2(3)4(1) states. Two distinct spectral signatures are identified, suggesting competition between dissociation pathways involving the X (1)A1 and the a (3)A2 potential energy surfaces. Most rovibrational states of H(2)CO(A 1A(2)) investigated in this work produceH+HCO(X (2)A') photofragments with a broad kinetic energy distribution and significant population in high energy rotational states of HCO. Photodissociation via the A (1)A2 2(2)4(3) 1(1,1) (and 1(1,0)) rovibronic states yields predominantly HCO fragments with low internal energy, a signature that these rovibronic levels are perturbed by the a (3)A2 state. The results also suggest the need for further careful measurements of the H+HCO quantum yield from H(2)CO photolysis at energies approaching, and above, the barrier to C-H bond fission on the a (3)A2 potential energy surface.
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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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".