Oscillation Bardeen-Friedel

In Fig. 4 we plot the correlation-kinetic field z[ (z) and observe that it too is concentrated about the surface. It is long-ranged in the vacuum, decaying asymptotically as a frO/z2. In the metal, it exhibits the requisite Bardeen-Friedel oscillations. c The field z[1)(z), however, is an order of magnitude smaller than the Pauli component field (z). 

In Fig. 5 the correlation-kinetic potential component Wt (z) is plotted. For these densities, the potential is entirely positive, possesses the correct asymptotic structure of Eq. (45) in the vacuum, and exhibits the Bardeen-Friedel oscillations. Once again, thepotential w[ z) is an order of magnitude smaller than the Pauli component Wx (z). For higher density metals (rs < 2), the correlation-kinetic contribution to vx(z) will be less significant. It will vanish entirely for the very slowly varying density case for which33,34 vx(z) = Wx (z). 

The x) values obtained from the 7-coupling measurements are plotted as a function ofx in Figure 10. It can be seen there that there is a clear oscillation in D Ej) across the spectrum. This represents the first experimental observation of a spatially-resolved oscillatory variation in A( f) caused by the presence of a metal surface. Moreover, the experimental results can be fit to a simple relationship, which has the essence of a Bardeen-Friedel oscillation," ... 

Moreover, the experimental results can be fit to a simple relationship, which has the essence of a Bardeen-Friedel oscillation, ... 

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