Figure 1

The surface-plasmon dispersion curves for the metals K, Na, Mg, Al, and Be as a result from taking spatial dispersion into account. The dotted curves are for the hydrodynamic approximation, the dashed curves are for the plasmon-pole approximation and the solid curves for RPA. Neglecting spatial dispersion would produce dispersionless horizontal curves at the values where the present curves start out from the frequency axis. The thick solid curve is the boundary of the single-particle continuum in the in-plane direction of the surface plasmon.Reuse & Permissions

Figure 2

The surface-plasmon dispersion curves for Be (upper solid curve) and Na (lower solid curve) in the range where retardation effects are visible. The dashed curve is the universal result when spatial dispersion is neglected. The retardation effects push the surface-plasmon dispersion curves down below the dispersion curve for light in vacuum (dotted straight line).Reuse & Permissions

Figure 3

The two TM-surface-mode branches for two half-spaces of gold separated by a gap of $1\mu \mathrm{m}$. The upper solid curve is just that part of a branch where the mode is a true surface mode, in that the fields decay exponentially away from the two interfaces on both sides. The dotted straight line is the light dispersion curve in vacuum. See the text for more details.Reuse & Permissions

Figure 4

The complete set of normal modes between gold plates (obtained in neglect of spatial dispersion) for roughly twice the separation of the setup in Fig. 3. The upper thick solid curve is the boundary for bulk-polariton-modes and the lower thick solid straight line is the light-dispersion curve. The thin solid curves are the true-surface-mode-type-modes, the dotted curves are the standing-wave-type TM modes and the dashed curves the standing-wave-type TE modes. Note that one of TM-mode branches changes character when crossing the light-dispersion curve.Reuse & Permissions

Figure 5

Energy correction factor as a function of the separation between two gold plates. The long-dashed curve is the Casimir perfect-metal result at zero temperature; it is by definition constant with value unity. The dash-dotted curve is the corresponding result at room temperature. The solid (dotted) curve is the room-temperature (zero-temperature) result from using the experimental dielectric function; these results include the effect of dissipation but neglect the spatial dispersion. The short-dashed curve (open circle) is the simple Drude result at zero temperature (room temperature); these results neglect both dissipation and spatial dispersion. The triangles is the present result including spatial dispersion; dissipation is neglected but the inclusion of dissipation leads to an overlapping result. The solid circles with error bars is the experimental result by Lamoreaux.Reuse & Permissions

Figure 6

The frequency integrands after the momentum integration has been performed. The integrands for the TM (TE) contribution at $1\mu \mathrm{m}$ separation are represented by a dashed (solid) curve. The curves with data points are the corresponding integrands at $5\mu \mathrm{m}$ separation. The crosses indicate the points that contribute to the summation at room temperature.Reuse & Permissions