Speciation and formation constants of aqueous lanthanum (III) chloride complexes from 5 to 80 °C by Raman spectroscopy
Bibliographic record
Abstract
Lanthanum chloride solutions were studied both computationally and by polarized Raman spectroscopy to determine the aqueous species present and their equilibrium constants. Four species were predicted from Gaussian 16 computations using density functional theory: La(H2O)93+, LaCl(H2O)82+, LaCl2(H2O)62+, and LaCl3(H2O)40. Both LaCl(H2O)82+ and LaCl2(H2O)6+ were identified in the reduced isotropic solvent-subtracted Raman spectra from their La–Cl vibrational bands at 234 and 221 cm−1, respectively. The spectra did not change significantly with temperature from 5 to 80 °C, and the Raman bands for each species could not be fitted with sufficient accuracy to determine the scattering coefficients directly from the experimental data. Instead, the computed scattering coefficients from Gaussian 16 (B3LYP with the Los Alamos National Laboratory 2-double-zeta effective core potential and 6-311+G(d,p) basis set) were to be used to obtain the equilibrium concentrations of LaCl(H2O)82+ and LaCl2(H2O)6+, from which the concentration of La(H2O)93+ was determined. The concentration dependent formation quotients were fitted with the specific ion interaction (SIT) activity coefficient model to determine the stepwise formation constants K0, 1 and K1, 2, from 5 to 80 °C. Both K0, 1 and K1, 2 showed minor increases with temperature.
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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 | 0.001 |
| 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 | 0.001 | 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".