Thallium Bromoiodide (KRS-5) ATR crystals are a medium refractive index material (2.37 @ 10 microns) with excellent long wavelength coverage in the infrared spectral region. It is non-hygroscopic with very good chemical resistance; however, KRS-5 will occasionally exhibit cold flow behavior. KRS-5 is extremely toxic and is absorbed through the skin and should only be handled with glove protection.

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