(A) Fluorescence autocorrelation functions for Cy7 (black) and the silver-DNA conjugate (red) emphasize the longer diffusion time of the latter through the laser probe volume. (B) Dependence of the shorter time scale dynamics on laser irradiance at 730 nm. Proceeding from the left, the irradiances are 0.3, 2, 5, and 30 kW/cm2. (C) Schematic energy level diagram rationalizing the photophysical behavior of the cluster-DNA conjugates. Fluorescence is derived from cycling through the ground and emissive states. Transitions into and from the dark state are determined by τon and τoff, respectively. Decay from this state is occurs by both natural decay and optical excitation.