Optical constants of some liquids for short electric waves.

J. D. Tear. The optical constants of certain liquids for short electrik Waves (Abstract).
Journ. of Franklin Inst. Vol. 194, No. 5, p. 685, Nov. 1922.

Over the unexplored region of the spectrum from the long infrared to short electric waves, the refraction and absorption of many substances undergo great changes.

Thus, for example, for water at \(\lambda = 0.3\) mm the refractive index is approximately the same as in the visible spectrum, while at \(\lambda = 30\) mm it is equal to 8.5, which is very close to the square root of the dielectric constant, as it should be for infinitely long electric waves. At present this region is being investigated (see the preceding abstract) by a more refined method than was previously available for waves of 27, 18, 11, 8, and 4 mm for the following liquids: water, glycerin, methyl and ethyl alcohol.

The refractive index is calculated by the Kohn–Quincke formula from the coefficients of reflection and absorption. In addition, an approximate value of the refractive index is obtained directly from the reflection of waves from the two surfaces of a liquid layer poured onto the surface of mercury; if the thickness of the layer is varied, the reflected energy passes through a series of maxima and minima, which make it possible to measure the wavelength in the liquid. The results obtained by the two methods agree well.

S. Rzhevkin.