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Cavity ring-down spectrometer for high-fidelity molecular absorption measurements
| Content Provider | Semantic Scholar |
|---|---|
| Author | Lin, Hongtao Reed, Zachary D. Sironneau, Vincent T. Hodges, Joseph T. |
| Copyright Year | 2015 |
| Abstract | Abstract We present a cavity ring-down spectrometer which was developed for near-infrared measurements of laser absorption by atmospheric greenhouse gases. This system has several important attributes that make it possible to conduct broad spectral surveys and to determine line-by-line parameters with wide dynamic range, and high spectral resolution, sensitivity and accuracy. We demonstrate a noise-equivalent absorption coefficient of 4×10 −12 cm −1 Hz −1/2 and a signal-to-noise ratio of 1.5×10 6 :1 in an absorption spectrum of carbon monoxide. We also present high-resolution measurements of trace methane in air spanning more than 1.2 THz and having a frequency axing with an uncertainty less than 100 kHz. Finally, we discuss how this system enables stringent tests of advanced line shape models. To illustrate, we measured an air-broadened carbon dioxide transition over a wide pressure range and analyzed these data with a multi-spectrum fit of the partially correlated, quadratic speed-dependent Nelkin–Ghatak profile. We obtained a quality-of-fit parameter in the multispectrum fit equal to 36,000, thus quantifying small-but-measurable limitations of the model profile. This analysis showed that the line shape depends upon collisional narrowing, speed dependent effects and partial correlations between velocity- and phase-changing collisions. |
| Starting Page | 11 |
| Ending Page | 20 |
| Page Count | 10 |
| File Format | PDF HTM / HTML |
| DOI | 10.1016/j.jqsrt.2015.03.026 |
| Volume Number | 161 |
| Alternate Webpage(s) | http://ws680.nist.gov/publication/get_pdf.cfm?pub_id=917321 |
| Alternate Webpage(s) | https://doi.org/10.1016/j.jqsrt.2015.03.026 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
