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We show that image-potential surface states are strongly affected by surface corrugation. In particular, their binding energy and effective mass are strongly coupled. New inverse-photoemission measurements for Ag(100) indicate that neglect of the corrugation contribution to the binding in previous work has caused (i) the confusion of the fundamental and excited image states and (ii) underestimation, by a factor of 3, of the spatial extent of the states observed.PACS numbers: 73.20.Cw, 79.20.Kz, 79.60.Cn We are concerned here with a special class of unoccupied electronic states that exist at solid surfaces. The potential that binds an electron to the surface in such a state is due to the response of the surface to the presence of the electron, i.e., the electron is bound to its own image. 1 ' 2 We want to emphasize that the physical origin of image states, which have now been observed on several metal surfaces by LEED 3 ' 4 and by inverse photoemission, 5 " 8 differs qualitatively from that of Shockley states 9 which are created at surfaces by the breaking of crystalline interatomic bonds. Unlike image states, the latter are part of the manifold of atomic valence states, and emerge, e.g., in a tightbinding description of a surface. 10 Unoccupied Shockley states have also been observed by inverse photoemission. 11 Image states are bound weakly to the surface, implying that their amplitude is concentrated relatively far away from it. 2,4 The physical picture of these states that we present is similar to that for electrons at semiconductor inversion layers, i.e., the electron is localized in one direction (z), but is nearly free in the remaining two directions (xand y). In the case of image states, because the localization is provided by a Coulomb potential, the z dependence of the wave function is fundamentally hydrogenic, with the crystal surface playing a role analogous to that of the atomic core in an alkali-metal atom (i.e., quantum defect). Interaction with the surface also perturbs the x,y dependence of the image-state wave function, causing motion along the surface to depart somewhat from free-electron behavior. This departure is measured directly in inverse-photoemission experiments as the effective mass. 6 ' 8 An important aspect of the present work is the observation that comcomitant with any deviation of the effective mass m" from unity is an increase of the image-state binding energy E B .That the binding energy and the effective mass are linked follows from general theoretical considerations, but determination of the magnitude of the effect requires either a detailed electronic-structure calculation for the surface, or accurate measurements of both the binding energy and the effective mass. Our measurements of these quantities for the (100) surface of Ag, shown in Fig. 1, indicate that, even on such dense surfaces, the surface-corrugation effect is not merely nonnegligible; it provides two-thirds of the image-state binding energy, and has caused the misidentification of image states previously obse...

Hypertriglyceridaemia, an atherogenic risk factor, is a well recognised complication of uraemia, and is present in the earliest stages of the disease. Bezafibrate is an effective hypolipidaemic agent, and its effect in moderate to severe uraemia is documented in this study. Significant reductions in serum triglyceride and cholesterol have been achieved after 1 month's therapy with a reduced dosage of bezafibrate. A reduction in the hyperinsulinaemia was also seen, but no change in the fractional removal rate of injected lipid emulsion (K2) was observed. An accelerated decline in some patients' renal function was observed, which was partially reversed on cessation of treatment. Reversible elevations in the serum creatinine phosphokinase were also seen, but no patient exhibited the myositis‐like syndrome associated with clofibrate.

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