Potassium bromide method of infrared sampling

In the preparation of potassium bromide pressed windows for use in the infrared analysis of solids, severe grinding of the potassium bromide powder may produce strong absorption bands that could interfere seriously with the spectra of the sample. These absorption bands appear to be due to some crystal alteration of the potassium bromide as a result of the grinding process. They were less apt to occur when the coarser powder, which had received a relatively gentle grinding, was used. Window blanks prepared from the coarser powders showed smaller adsorbed water peaks and generally higher over-all transmittance readings than windows pressed from the very fine powders.