Interpretations of High-Order Transient Absorption Spectroscopies
Bibliographic record
Abstract
Transient absorption (TA) spectroscopy is an invaluable tool for determining the energetics and dynamics of excited states. When pump intensities are sufficiently high, TA spectra include both the generally desired third-order response and responses that are higher in order in the field amplitudes. Recent work demonstrated that pump-intensity-dependent TA measurements allow separating the orders of response, but the information content in those higher orders has not been described. We give a general framework for understanding high-order TA spectra. We extend to higher order the fundamental processes of standard TA: ground-state bleach (GSB), stimulated emission (SE), and excited-state absorption (ESA). Each order introduces two new processes: SE and ESA from previously inaccessible highly excited states and negations of lower-order processes. We show the new spectral and dynamical information at each order and show how the relative signs of the signals in different orders can be used to identify which processes dominate.
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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 | 0.002 | 0.009 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.003 |
| Scholarly communication | 0.003 | 0.004 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.011 | 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".