Figure 2.

This fluorescence experiment illustrates the mixing process. The field of view shows only the innermost capillary tube at the ‘Mixing Region’ indicated in Fig. 1 ▶. (a) Fluorescent dye in the inner line, water in the outer line. (b) Fluorescent dye in the inner line, quencher in the outer line. Quenching represents the mixing process. A blue background is seen along the lower edge of each image.