  Measurements of visible and near-infrared reflection (0.38-5 {\mu}m) and mid
to far infrared emission (5-200 {\mu}m) from telescope and satellite remote
sensing instruments make it possible to investigate the composition of
planetary surfaces via electronic transitions and vibrational modes of chemical
bonds. Red spectral slopes at visible and near infrared wavelengths and
absorption features at 3.3 and 3.4 {\mu}m observed in circumstellar disks, the
interstellar medium, and on the surfaces of solar-system bodies are interpreted
to be due to the presence of organic material and other carbon compounds.
Identifying the origin of these features requires measurements of the optical
properties of a variety of relevant analog and planetary materials.
Spectroscopic models of dust within circumstellar disks and the interstellar
medium as well as planetary regoliths often incorporate just one such
laboratory measurement despite the wide variation in absorption and extinction
properties of organic and other carbon-bearing materials. Here we present
laboratory measurements of transmission spectra in the 1.5-13 {\mu}m region and
use these to derive real and imaginary indices of refraction for two samples:
1) an analog to meteoritic insoluble organic matter and 2) a powdered Allende
meteorite sample. We also test our refractive index retrieval method on a
previously published transmission spectrum of an Mg-rich olivine. We compare
optical measurements of the insoluble organic-matter analog to those of other
solar-system and extrasolar organic analogs, such as amorphous carbon and
tholins, and find that the indices of refraction of the newly characterized
material differ significantly from other carbonaceous samples.
