Primary Gas Thermometry by Means of Laser-Absorption Spectroscopy: Determination of the Boltzmann Constant

Casa, Giovanni Della; Castrillo, A.; Galzerano, G.; Wehr, Richard; Merlone, A.; Serafino, Daniela di; Laporta, P.; Gianfrani, L.

doi:10.1103/physrevlett.100.200801

Cited by 89 publications

(80 citation statements)

References 14 publications

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“…independently of pressure, i and j referring to a pair of NH 3 lines. This comes from the linear dependence of the Doppler width (HWHM) on the line-center frequency, according to the well-known formula…”

Section: Resultsmentioning

confidence: 99%

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Frequency-comb-calibrated Doppler broadening thermometry

Gatti

Mills²,

Vizia³

et al. 2013

Phys. Rev. A

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We describe an implementation of Doppler broadening thermometry based upon a room-temperature continuous-wave quantum cascade laser at 9.07 μm, coherently phase locked to a thulium optical frequency comb centered at 2 μm. The thermodynamic temperature is retrieved from the analysis of multiple-line absorption spectra of the NH 3 ν 2 band, adopting semiclassical line-shape models and taking into full account the speed dependence of collisional broadening. We demonstrate that a precision of approximately five parts over 10 5 can be reached as a result of the analysis of only 90 absorption spectra, as acquired as a function of the gas pressure.

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Section: Resultsmentioning

confidence: 99%

“…In the former case a narrow CO 2 laser, frequency stabilized on an OsO 4 saturated absorption line, was used to probe a strong 14 NH 3 line at 10.34 μm [2]. In the subsequent implementation an extended-cavity diode laser (ECDL) at 2 μm was used to interrogate a vibration-rotation transition of CO 2 [3].…”

Section: Introductionmentioning

confidence: 99%

Frequency-comb-calibrated Doppler broadening thermometry

Gatti

Mills²,

Vizia³

et al. 2013

Phys. Rev. A

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“…Other groups followed our initiative in measuring k B using the DBT, but probing other species such as CO 2 , H 2 O, C 2 H 2 and Rb [43,[52][53][54][55]. Table 1 gives the corresponding state-of-art for the statistical uncertainty obtained on k B .…”

Section: Statistical Uncertaintymentioning

confidence: 99%

Accurate determination of the Boltzmann constant by Doppler spectroscopy: Towards a new definition of the kelvin

Darquié

Mejri

Sow

et al. 2013

EPJ Web of Conferences

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Abstract. Accurate molecular spectroscopy in the mid-infrared region allows precision measurements of fundamental constants. For instance, measuring the linewidth of an isolated Doppler-broadened absorption line of ammonia around 10 m enables a determination of the Boltzmann constant k B . We report on our latest measurements. By fitting this lineshape to several models which include Dicke narrowing or speeddependent collisional effects, we find that a determination of k B with an uncertainty of a few ppm is reachable. This is comparable to the best current uncertainty obtained using acoustic methods and would make a significant contribution to any new value of k B determined by the CODATA. Furthermore, having multiple independent measurements at these accuracies opens the possibility of defining the kelvin by fixing k B , an exciting prospect considering the upcoming redefinition of the International System of Units.

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“…By measuring a NH 3 line near 10 µm, they determined the k B value with a relative uncertainty of 2×10 −4 [12], and later on 5 × 10 −5 [13,14]. The Italian group at Seconda Università di Napoli obtained an accuracy of 160 ppm using a CO 2 line at 2.006 µm [15], and recently improved the accuracy to 24 ppm by measuring an absorption line of H 18 2 O near 1.39 µm [16].…”

Section: Introductionmentioning

confidence: 99%

Doppler Broadening Thermometry Based on Cavity Ring-Down Spectroscopy

Hu¹

2014

Proceedings of the 69th International Symposium on Molecular Spectroscopy

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Abstract. A Doppler broadening thermometry (DBT) instrument is built based on cavity ring-down spectroscopy (CRDS) for precise determination of the Boltzmann constant. Compared with conventional direct absorption methods, the high-sensitivity of CRDS allows to reach a satisfied precision at lower sample pressures, which reduces the influence due to collisions. By recording the spectrum of C 2 H 2 at 787 nm, we demonstrate a statistical uncertainty of 6 ppm (part per million) in the determined linewidth values by several hours' measurement at a sample pressure of 1.5 Pa. As for the spectroscopy-determined temperatures, although with a reproducibility better than 10 ppm, we found a systematic deviation of about 800 ppm, which is attributed to "hidden" weak lines overlapped with the selected transition at 787 nm. Our analysis indicates that it is feasible to pursue a DBT measurement toward the 1 ppm precision using cavity ring-down spectroscopy of a CO line at 1.57 mum.

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Primary Gas Thermometry by Means of Laser-Absorption Spectroscopy: Determination of the Boltzmann Constant

Cited by 89 publications

References 14 publications

Frequency-comb-calibrated Doppler broadening thermometry

Frequency-comb-calibrated Doppler broadening thermometry

Accurate determination of the Boltzmann constant by Doppler spectroscopy: Towards a new definition of the kelvin

Doppler Broadening Thermometry Based on Cavity Ring-Down Spectroscopy

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