Figure 6.

Separation of the source fibers promotes synchrony and uniformity of the NO volume signal. Local NO concentrations generated during and after 1 s of synthesis by an ordered array of 10 × 10 fibers (fiber diameter of 1 μm), measured at three points: at the center of the array (solid lines) and 50 μm (dashed lines) and 100 μm (dotted lines) away from the center. The duration of synthesis indicated by gray rectangles in bottom row. Top row, Points of measurement and fiber profiles (black dots) superimposed on a snapshot of the spatial NO distribution (shaded) at the end of synthesis (arrows). A, Fibers separated by 25 μm. The entire region synchronously experiences a very similar time course of NO that is characterized by a relatively slow and approximately linear rise and fall. B, Fibers arranged contiguously so they act as a single 10 × 10 μm source. The center instantaneously experiences concentrations far in excess of 100 nm; rise and fall are highly nonlinear. Points away from the center encounter a much slower rise and fall with different temporal characteristics depending on their distance from the center. In particular, the farther from the center, the longer NO continues to rise after the end of synthesis.