A Radiometric Determination of the Thermodynamic Temperature Interval between the Silver and Gold Freezing Points

A new measurement of the thermodynamic temperature interval between the silver and the gold freezing points with an infrared pyrometer has been carried out. The value of the freezing point of gold, referred to the value of the silver point on the IPTS-68, thus obtained, is 1337.41 K (σ = 0.059 K). The ratio of the spectral radiances at the two points is 2.4428 (σ = 1.2 · 10 -3 ) at the mean effective wavelength λ e = 0.9980μm (σ= 0.3 nm). The resulting temperature interval is 0.17 K shorter than the IPTS-68 interval between the same points.