UF-CRDS: A PULSED UNIFORM FLOW APPARATUS WITH CW-CAVITY-RINGDOWN SPECTROSCOPY
Bibliographic record
Abstract
We introduce a new apparatus in which a high-performance pulsed supersonic uniform flow from a Laval nozzle is coupled with a continuous wave cavity ringdown spectroscopy (cw-CRDS). This approach is related to the CRESU\\footnote{Sims,I., Queffelec, J.L., Defrance,A., Rebrion-Rowe,C., Travers,D., Bocherel, P., Rowe, B., and Smith, I.W.M., J. Chem. Phys. 100 (6), 4229-4241 (1994).} technique developed in France to study reaction kinetics at low temperature. A related system developed in our group in which chirped-pulse microwave spectroscopy is coupled to a pulsed Laval flow has successfully demonstrated its investigative capability of isomer-specific product branching in reactions and photodissociation at temperatures as low as 22 K\\footnote{Broderick, B.M., Suas-David, N., Dias, N., and Suits, A.G., Phys. Chem. Chem. Phys. 20 (8), 5517-5529 (2018).}.\nThe pulsed uniform flow is produced by means of a high throughput piezoelectric stack valve combined with a Laval nozzle.\\footnote{Oldham, J.M., Abeysekera, C., Joalland, B., Zack, L.N., Prozument, K., Sims, I.R., Park, G.B., Field, R.W., and Suits, A.G., J. Chem. Phys. 141 (15), 154202 (2014).}At present, we employ two machined aluminum nozzles (for carrier gases He and Ar at temperatures around 25 K), and numerous in-house 3D printed nozzles. The 3D printed nozzles are designed using a Matlab program developed in-house, which allows us to create supersonic uniforms flows with different carrier gases at various temperature and densities. These nozzles are validated experimentally as well as theoretically using a computational fluid dynamics program, OpenFOAM. \n\nThe current configuration can probe the pulsed uniform flow either by cw-CRDS, operated in the near infrared region, or laser-induced fluorescence as in the traditional CRESU approach. The cw-CRDS spectrometer consists of a high finesse optical cavity (F~200000) which is composed of two high reflective plano-concave mirrors (R~99.9988\\%) leading to an empty cavity decay constant of ~160 $\\mu$s. We adopt a modified version of the timing strategy which was reported by Hippler M. et al\\footnote{Hippler, M., and Quack, M., M Hippler, et.al, Chem. Phys. Lett. 314 (3), 273-281 (1999).} in order to probe reactants of bimolecular reactions formed from photolysis. We will present our first low temperature kinetics experiments performed with this apparatus including reaction of CN (v=1) with alkenes probed by cw-CRDS.
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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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 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".