For the nanoparticle systems, the series approximation for the Kaptiza resistance in Eq. ( ) was used to compute G. Because the citrate and sodium counter ions form diffuse layers surrounding the particles, defining the overall width of the interface is important to capturing the interfacial conductance. The inner radius for the interface was set to 17.75 Å, a radius which is unambiguously inside the gold particle (see Fig. ), and G was calculated from that location to an outer boundary that was unambiguously within the solvent cloud. In Fig. , we also indicate the inner boundary of the Kapitza series approximation and the range of values for the outer boundary of this region. Tabulated G values using Eq. ( ) for the nanosphere systems are given in Table . Despite varying the interfacial widths, the calculated value of G remains relatively stable. The use of the continuity equation, Eq. ( ), for the spherical systems requires projecting a temperature drop at the location of the nanoparticle surface. This results in a significant underestimate of the temperature drop from the particle surface across the diffuse citrate-water layers.