Knowledge Bank

All available literature on the infrared optical indices of MgO has been critically examined with particular emphasis on the Kramers-Kronig (KK) dispersion analysis of room temperature reflectance data.$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ Using the equivalent critical frequency partitioning technique, originally suggested by $Wu,2$ a significant distortion has been uncovered in the KK phase angle spectrum furnished by $Piriou3,4$ as being due to high values of reflectance in the minimum relfectance $(RMin)$ region. Careful experimental remeasurements quantitatively support this qualitative disclosure. The new input reflectance data in the $RMin$ region may be considered to be significant on two other accounts: (1) the resultant KK output absorption index values are in excellent agreement with experimental measurements in contrast with published data, and (2) the new reflectance values agree well with values predicted by the mathematical formulation of Wu and $Andermann,5$ and thus represent the first experimental verification of this method.