Thallium Bromoiodide KRS

To prepare a film one allows a solution of the sample to evaporate slowly on the face of a suitable window material. The plate may be gradually heated if necessary. For many compounds this means dissolution in a volatile organic solvent, and an alkali halide plate is used. Films of such substances as proteins and mucopolysaccharides have frequently been cast from aqueous solution on a silver chloride plate. IRTRAN-2 (ZnS) and KRS-5 (thallium bromoiodide) plates can also be used. 

One of the more useful predictions from the model is that the absorption peak from Equation 16.20 is proportional to the square root of the lattice stiffness divided by the reduced mass of the ion pairs. In the design of glasses and other optical components that must operate in the far-infrared, one wants to operate at frequencies well above the absorption at ca = 2/3//a. Therefore, one looks for materials with heavy ion pairs and low soimd velocities. Single crystalline NaCl is used for infrared windows out to about 15 pm while KBr is good out to about 25 pm. KRS-5, (thallium bromoiodide) is used for infrared applications out to 35 pm. The development of heavy metal glasses is discussed further in Chapters 14 and 24. 

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