THE INFRARED REFRACTIVE-INDEXES OF CHBR3, CCL4 AND CS2

Spectrally resolved data for the real part, n(lambda), of the complex refractive index, n = n + ik, of bromoform (tribromomethane, CHBr3) at room temperature (298 K) in the wavelength range 1-13 mum are presented. The measurements were made using the near-normal reflectance technique. The accuracy of the method was confirmed by comparing measured values of n(lambda) of water with available data in the literature. For bromoform, n(lambda) is found to decrease gradually from 1.58 to 1.51 over this wavelength range, except in the region of anomalous dispersion near absorption bands at 3.3 and 8.7 mum. A complete infrared window for extinction measurements on suspended particulates can be obtained using CCl4 in the spectral range 1-6 mum, CHBr3 in the ranges 6.0-7.4 mum and 11-13 mum, and CS2 in the range 7.4-11.0 mum. The data for n(lambda) of CCl4 in the range 1-9 mum, and those for CS2 in the range 7.4-11.0 mum, obtained from reflectance measurements, compare favorably with data available in the literature.