Germanium (Ge) is an optical material commonly used in infrared spectroscopy. It has very high refractive index of 4.0, and a relatively narrow spectral range compared to diamond.

Germanium's high refractive index value makes it the ATR prism of choice for materials with a high refractive index, which include materials with very strong chemical bonds or materials such a carbon black. Both type of materiasl can have infrared spectra that appear distorted when measured on lower refractive index ATR prisms such as ZnSe or diamond.  Germanium ATR prisms are superior to ATR correction algorithms.

Germanium ATR spectra are substantially closer in appearence to transmission spectra than are ZnSe or Diamond ATR spectra. 

These four  FDM Germanium ATR libraries 

• FDM ATR Polymers Germanium

• FDM ATR Organics Germanium

• FDM ATR Inorganics Germanium

• FDM ATR Dyes Germanium

are all part of the the FDM ALL ATR Bundle and are perfectly reasonable choices when searching transmission spectra.  ATR spectra have the further advantage of being far more reproducible sampling than transmission spectra.  

Special note: The high AOI (Angle Of Incidence) spectra, about 58 degrees, in the FDM Multiangle ATR Polymers are similar to 45 degree AOI Germanium ATR spectra, and transmission spectra, having near zero anomolous dispersion present in conventional 45 degree ATR spectra run on Diamond or ZnSe ATR crystals(prisms).

We publish: 

•  numerous FTIR  and ATR/FTIR libraries, covering polymers, drugs, organic and inorganic compounds, and more, either individually or in bundles, and

• the FDM SearchFaster™ software, for searching unknown spectra against the FDM FTIR libraries.

We offer our libraries and software via a one-time license fee or on a subscription basis.