Radiolysis of Liquid Water at Temperatures up to 300 °C: A Monte Carlo Simulation Study
Bibliographic record
Abstract
Monte Carlo simulations were performed to calculate the temperature dependence of the primary yields ( g -values) of the radical and molecular products of the radiolysis of pure, deaerated liquid water by low linear-energy-transfer (LET) radiation. The early energy deposition was approximated by considering short segments (∼100 μm) of 300-MeV proton tracks (corresponding to an average LET of ∼0.3 keV/μm). The subsequent nonhomogeneous chemical evolution of the reactive species formed in these tracks was simulated by using the independent reaction times approximation, which has previously been used successfully to model the radiolysis of liquid water at ambient temperature under various conditions. Our calculated g -values for the radiolytic species:, OH, H, H 2, and H 2 O 2, are presented as a function of temperature over the range 25−300 °C. They show an increase in g ( ), g (OH), and [ g (H) + g (H 2 )] and a decrease in g (H 2 O 2 ) with increasing temperature, in agreement with existing experimental data. The sensitivity of the results to the values of reaction rate constants and to the temperature dependence of electron thermalization distances ( r th ) was also investigated. It was found that the best agreement with experiment occurs when the distances of electron thermalization decrease with increasing temperature, a result that is at variance with the predictions of previous modeling studies. Such a decrease in r th as the temperature increases could be linked to an increase in the scattering cross sections of subexcitation electrons that would account for the corresponding decrease in the degree of structural order of water molecules. Our simulations also suggest that the variations of the g -values with temperature, and especially that of g (H 2 ), are better described if we account for the screening of the Coulomb forces between the two in the bimolecular self-reaction of the hydrated electron. Finally, the time-dependent yields of and OH are presented as functions of temperature, in the range 10 -12 −10 -6 s. It was found that the temporal variation of g ( ) at elevated temperatures is sensitive to the temperature dependence of r th, suggesting that measurements of the decay of hydrated electrons as functions of time and temperature could, in turn, provide information on the thermalization of subexcitation electrons. The good overall accord of our calculated results with the experimental data available from the literature demonstrates that Monte Carlo simulation methods offer a most promising avenue at present to further develop our understanding of temperature effects in the radiolysis of liquid water.
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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 | 0.000 |
| 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 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".