arXiv subjects

Katarzyna Bielska

Publications and source records attributed to Katarzyna Bielska.

4 recordsLinked to original sources

arXiv2025

Leveraging resonant frequencies of an optical cavity for spectroscopic measurement of gas temperature and concentration

We introduce a spectroscopic approach to primary gas thermometry, harnessing precise optical cavity resonance frequencies and ab initio molecular line intensity calculations. By utilizing CO (3-0) vibrational band lines and cavity mode dispersion spectroscopy, we achieve an uncertainty of 82 ppm (24 mK at 296 K) in line-intensity-ratio thermometry (LRT) - over an order of magnitude lower than any previously reported spectroscopic thermometry at gas pressures above 1.2 kPa. This method extends high-precision spectroscopic thermometry across a pressure range an order of magnitude larger than prior techniques, enabling a fully optical, non-contact, and molecule-selective primary amount-of-substance measurement. We further demonstrate sub-permille uncertainty in gas concentration measurements across pressures from 50 Pa to 20 kPa, significantly enhancing the precision and versatility of spectroscopic gas metrology.

physics.optics↗

arXiv2024

Heterodyne dispersive cavity ring-down spectroscopy exploiting eigenmode frequencies for high-fidelity measurements

Measuring low light absorption with combined uncertainty < 1 permille is crucial in a wide range of applications. Popular cavity ring-down spectroscopy can provide ultra-high precision, below 0.01 permille, but its accuracy is strongly dependent on the measurement capabilities of the detection system and typically is about 10 permille. Here, we exploit the optical frequency information carried by the ring-down cavity electromagnetic field, not explored in conventional CRDS, for high-fidelity spectroscopy. Instead of measuring only the decaying light intensity, we perform heterodyne detection of ring-downs followed by Fourier analysis to provide exact frequencies of optical cavity modes and a dispersive spectrum of a gas sample from them. This approach is insensitive to inaccuracies in light intensity measurements and eliminates the problem of detector band nonlinearity, the main cause of measurement error in traditional CRDS. Using the CO and HD line intensities as examples, we demonstrate the sub-permille accuracy of our method, confirmed by the best ab initio results, and the long-term repeatability of our dispersion measurements at 10^(-4) level. Such results have not been achieved in optical spectroscopy before. The high accuracy of the presented method indicates its potential in atmospheric studies, isotope ratio metrology, thermometry, and the establishment of primary gas standards.

physics.optics↗

arXiv2015

High accuracy CO$_2$ line intensities determined from theory and experiment

Atmospheric CO$_2$ concentrations are being closely monitored by remote sensing experiments which rely on knowing line intensities with an uncertainty of 0.5\%\ or better. Most available laboratory measurements have uncertainties much larger than this. We report a joint experimental and theoretical study providing rotation-vibration line intensities with the required accuracy. The {\it ab initio} calculations are extendible to all atmospherically important bands of CO$_2$ and to its isotologues. As such they will form the basis for detailed CO$_2$ spectroscopic line lists for future studies.

physics.ao-ph↗

arXiv2009

Buffer gas induced collision shift for the $^{88}$Sr $\bf{^1S_0-^3P_1}$ clock transition

Precision saturation spectroscopy of the $^{88}{\rm Sr} ^1S_0-^3P_1$ is performed in a vapor cell filled with various rare gas including He, Ne, Ar, and Xe. By continuously calibrating the absolute frequency of the probe laser, buffer gas induced collision shifts of $\sim $kHz are detected with gas pressure of 1-20 mTorr. Helium gave the largest fractional shift of $1.6 \times 10^{-9} {\rm Torr}^{-1}$. Comparing with a simple impact calculation and a Doppler-limited experiment of Holtgrave and Wolf [Phys. Rev. A {\bf 72}, 012711 (2005)], our results show larger broadening and smaller shifting coefficient, indicating effective atomic loss due to velocity changing collisions. The applicability of the result to the $^1S_0-^3P_0$ optical lattice clock transition is also discussed.

physics.atom-ph↗