PN 350-025004-09
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Germanium
Germanium (Ge) has been used extensively in the past as a higher refractive index material for samples
that have a high refractive index, such as carbon filled samples. The down side of using Ge is the high
refractive index produces a relatively weaker spectral absorbance compared to ZnSe or diamond.
Silicon
Silicon is hard and brittle. It is chemically inert and only strong oxidizers affect it. Silicon is well suited for
applications requiring temperature changes as it withstands thermal shocks better than other ATR
materials. It also is the hardest crystal material offered except for diamond, which makes it well suited
for abrasive samples that might otherwise scratch softer crystal materials. Typically, Silicon crystal is
totally absorbing below 1500 cm
-1
making its usefulness in the mid-IR range limited.
Diamond
Diamond is one of the most rugged optical materials. It can be used for analysis of a wide range of
samples, including acids, bases, and oxidizing agents. Diamond is also scratch and abrasion resistant. Its
disadvantage is the cost and the intrinsic absorption from approximately 2300 to 1800 cm
-1
, which limits
its usefulness in this region (5% transmission).
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