Study of a soft x-ray (1-5 nm) laser plasma source for femtosecond time resolved XAS
Bibliographic record
Abstract
The dynamics of ultrafast phase transition and reaction mechanisms can be deduced from ultrafast x-ray diffraction or absorption measurements. Femtosecond lasers have been used recently to study matter dynamics with optical-pump and x-ray probe spectroscopy, using monochromatic K alpha x-ray radiation. We present here our most recent progress in the development of a femtosecond time- resolved x-ray absorption spectroscopy (XAS) system based on a broadband soft x-ray source in the 1-5 nm range. The femtosecond XAS system is designed to probe the electronic dynamics occurring during the vanadium dioxide (VO<sub>2</sub>) semiconductor to metal phase transition following excitation by a femtosecond laser pulse. In the present experiments, broadband spectra near the vanadium L edge (511 eV) and oxygen K edge (525 eV) of VO<sub>2</sub> have been generated and measured with simultaneously high signal to noise ratio (100), high spectral resolution (ΔE/E=4x10<sup>-3</sup>) and a 1.2 ps temporal resolution.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| 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) | 0.000 | 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".