Effect of Resolution on the Wavelength Determination of a Putative Standard to Be Used for near Infrared Diffuse Reflection Spectra Measured on Grating Spectrometers

Abstract

Diffuse reflection (DR) Fourier transform near infrared spectra of a powdered mixture of Er₂O₃, Dy₂O₃, Ho₂O₃ and talc were measured at a constant resolution of at least 2 cm⁻¹ on four different combinations of spectrometers and sampling accessories. The wavenumber scale of each of these spectra was corrected with lines in the vibration–rotation spectrum of water vapour so that the accuracy was better than 0.02 cm⁻¹. DR spectra of the powdered sample were then calculated at constant-wavelength resolution to simulate spectra that would have been measured on a grating monochromator. The precision and accuracy of the bands in the spectrum of this sample were then estimated. It is believed that the accuracy of the reported positions of the bands in the spectrum of this putative wavelength standard is about ten times better than the corresponding values in the DR spectrum of a mixture of Er₂O₃, Dy₂O₃ and Ho₂O₃ that had previously been reported by the US National Institute of Standards and Technology.