For a cell used in the infrared analysis of gases, the best choice of window material is KCl (potassium chloride). KCl is inexpensive, it transmits the entire fundamental infrared spectral region, and it is not especially hygroscopic. It is less hygroscopic and less expensive than KBr. If the potassium chloride windows become degraded through mis-use, they can be thrown away and replaced without serious expense.

Return to Table of Contents