Silicon halides methylene

Less common situations to consider are when studies of surface contamination are required and when the surface cannot be separated and brought to the instrument. In the first example, a practical solution is to grind a small amount of alkali halide powder (KBr or KCl) at the point of the contamination. This will result in the transfer of some of the contaminant to the alkali halide, and this in turn may be examined either by the compressed pellet technique or by diffuse reflectance. A way to assist this surface extraction is to add a few drops of a solvent, such as methylene chloride, in the area of the contamination. In the second situation, sampling may be performed by gently abrading the surface with silicon carbide paper. This action will transfer a small amount of the surface to the abrasive paper, and this in turn may be examined with the aid of a diffuse reflectance accessory. 

---