Raman spectroscopic observations of methane-hydrate formation and hydrophobic hydration around methane molecules in solution
Bibliographic record
Abstract
To reveal the hydrophobic hydration process of methane molecules dissolved in water, Raman spectra of dissolved methane (CH4) in water were measured under various conditions. The conditions include water saturated with CH4 gas, waterCH4 solution with CH4 hydrate crystals in equilibrium, and also during hydrate decomposition. The symmetric CH stretching mode of the CH4 molecule in water is a single peak at 2910 cm1 with a half-width of approximately 5 cm1. These results indicate that the size of the space for the CH4 molecules, called the hydration shell, is between the large and small cages of the hydrate crystal, but it has a broad size distribution. To better understand the CH4-molecule vibrations, its spectrum in water was compared with its spectra in liquid carbon dioxide (CO2) and in liquid ethane (C2H6). These spectra were very similar to those observed in water, except that the peak widths were sharper than those in water. This suggests that the broadening of the shell-size distribution is due to the way the CH4 molecules affect the hydration shell. On the other hand, when the system included hydrate crystals, a double CH4 peak arose due to structure in the aqueous solution near the crystal surface. This indicates that a cage-like structure can exist in the water phase. Compared with the decomposition experiment, the cage-like structure is likely due to the presence of the bulk hydrate crystal and is different from the hydration shell for the dissolved CH4 molecules. PACS Nos.: 81.10Dn, 33.20Fb
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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) | 0.001 | 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".