A MULTI-REFLECTION RAMAN CELL FOR STUDYING DILUTE AQUEOUS-SOLUTIONS

A cell for multi-reflection Raman measurements was constructed. This device consists of two rectangular prisms and, when applied to a rectangular sample cell, Raman signals were enhanced by seven to ten times compared with the single-pass measurement for a transparent solution. This system is readily applicable to studies of dilute aqueous solutions with low refractive indices. With this device, the C-H stretching Raman bands of benzene in water were observed with sufficiently high S/N ratios. Combination of the multi-pass cell with an optical-fiber light-collecting device enabled us to determine reproducibly the shifts of Raman bands from some reference state with an accuracy of 0.006 cm-1.