 Some experimenters have substituted fluoride for chloride ion because fluoride absorbs less in the far UV, and some have worked in pure water.Another, almost universal, technique is to minimize solvent absorption by using shorter path length cells when working in the far UV, 0.1 mm path lengths are not uncommon in this work.In addition to measuring in aqueous systems, CD, particularly far-UV CD, can be measured in organic solvents e.g.