Extinction coefficients k(lambda) for water at 25 degrees C were determined through a broad spectral region by manually smoothing a point by point graph of k(lambda) vs wavelength lambda that was plotted for data obtained from a review of the scientific literature on the optical constants of water. Absorption bands representing k(lambda) were postulated where data were not available in the vacuum uv and soft x-ray regions. A subtractive Kramers-Kronig analysis of the combined postulated and smoothed portions of the k(lambda) spectrum provided the index of refraction n(lambda) for the spectral region 200 nm

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Measurements of the optical constants of metals at submillimeter wavelengths are sparse. We have used a nonresonant cavity to measure, at room temperature, the angle averaged absorptance spectra P(omega) of aluminum, molybdenum, tantalum, titanium, tungsten, and iron in the 30-300-cm(-1) wavenumber region. The real part of the normalized surface impedance spectrum, z(omega) = r(omega) + ix(omega), was determined from P(omega). Measurements were also made on iron from 400 to 4000 cm(-1) using standard reflectance techniques. The r(omega) spectrum was combined with previous measurements by others at higher frequencies and Kramers-Kronig analyses of the resultant combined r(omega) spectra provided epsilon(omega) = epsilon(1)(omega) + iepsilon(2)(omega) and N(omega) = n(omega) + ik(omega).

We designed an improved wedge shaped cell for measuring Lambert absorption coefficient spectra alpha(nu) of highly absorbent liquids. The design allows for accurate determination of the apex angle of the wedge, sealing the cell, and injection of the liquid without disassembling the cell. We measured alpha(nu) for water through the 500-12,500-cm(-1) wavenumber region to determine the range of alpha(nu) for which the cell provided accurate measurements. We then determined the imaginary part of the complex refractive index N(nu) = n(nu) + ik(nu) from alpha(nu) and used Kramers-Kronig methods to compute n(nu) from k(nu).

Measurements of the optical properties, and thus the optical constants, of metals at submillimeter wavelengths are almost nonexistent. We used a nonresonant cavity to measure at ambient temperature the angle averaged absorptance spectra P(omega) of gold, nickel, and lead in the 30-300-cm(-1) wave-number region. The real part of the normalized surface impedance spectrum z(omega) = r(omega) + ix(omega) was determined from P(omega). The r(omega) spectrum was combined with previous measurements by others at higher frequencies, and Kramers- Kronig analyses of the resultant r(omega) spectra provided (omega) =, (1) (omega) + i(2)(omega) and N(omega) = n(omega) + ik(omega) for gold and nickel in the 35-15,000-cm(-1) region and for lead in the 15-15,000-cm(-1) region. We also derived an exact analytical expression for P(omega) of a metal.