Temperature gradients, wavelength-dependent emissivity, and accuracy of high and very-high temperatures measured in the laser-heated diamond cell

We have spectrorachometrically measured a suite of temperatures between 761 +/- 128 and 7307 +/- 958 K in the laser-heated diamond cell using Br-2 sample material. Critical evaluation of each spectrum and the dataset as a whole in comparison with synthetic data confirms the high temperatures and demonstrates the observable effects of temperature gradients and wavelength-dependent emissivity or absorbance on a single spectrum. In addition, we quantitatively demonstrate the use of a sliding two-color pyrometer analysis to produce a consistent and meaningful estimate of uncertainty of spectral temperature measurements.