Laser refractometers are approaching accuracy levels where gas pressures in the range 1 Pa < p < 1 MPa inferred by measurements of gas refractivity at a known temperature will be competitive with the best existing pressure standards and sensors. Here, the authors develop the relationship between pressure and refractivity p = c 1 ⋅ ( n - 1 ) + c 2 ⋅ ( n - 1 ) 2 + c 3 ⋅ ( n - 1 ) 3 + ⋯ , via measurement at T = 293.1529(13) K and λ = 632.9908(2) nm for p ≤ 500 kPa. The authors give values of the coefficients c 1, c 2, c 3 for six gases: Ne, Ar, Xe, N2, CO2, and N2O. For each gas, the resulting molar polarizability A R ≡ 2 R T 3 c 1 has a standard uncertainty within 16 × 10-6·A R . In these experiments, pressure was realized via measurements of helium refractivity at a known temperature: for He, the relationship between pressure and refractivity is known through calculation much more accurately than it can presently be measured. This feature allowed them to calibrate a pressure transducer in situ with helium and subsequently use the transducer to accurately gage the relationship between pressure and refractivity on an isotherm for other gases of interest.

中文翻译：

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在激光气压计中测量六种候选气体的热力学压力和折射率之间的关系。

激光折光仪正在接近精度水平，通过测量已知温度下的气体折射率推断出 1 Pa < p < 1 MPa 范围内的气压将与现有最好的压力标准和传感器竞争。在这里，作者通过在 T = 293.1529 处的测量，建立了压力和折射率之间的关系 p = c 1 ⋅ ( n - 1 ) + c 2 ⋅ ( n - 1 ) 2 + c 3 ⋅ ( n - 1 ) 3 + ⋯ (13) 当 p ≤ 500 kPa 时，K 和 λ = 632.9908(2) nm。作者给出了六种气体的系数 c 1、c 2、c 3 值：Ne、Ar、Xe、N2、CO2 和 N2O。对于每种气体，所得的摩尔极化率 AR ≡ 2 RT 3 c 1 的标准不确定度在 16 × 10-6·AR 内。在这些实验中，压力是通过测量已知温度下的氦折射率来实现的：对于氦，通过计算可以知道压力和折射率之间的关系，这种关系比目前测量的精度要高得多。这一功能使他们能够用氦气现场校准压力传感器，然后使用传感器准确测量其他感兴趣气体的等温线上的压力和折射率之间的关系。