Rafael Garcia-Molina

The impedance boundary condition for a curved surface

Abstract We describe a systematic method for obtaining the impedance boundary condition for a p- or s-polarized electromagnetic field at the curved boundary between vacuum and a metal as an expansion in powers of the skin depth of the field in the metal. The surface is defined by the equation x3 = ζ(x1), and the plane of incidence is the x1x3-plane. The first three terms in this expansion are obtained, and the conditions under which the result is valid are discussed. The boundary condition obtained is used in a determination of the dispersion curves for surface polaritons propagating across a one-dimensional metallic grating.

Proton energy loss in allotropic forms of carbon

We have investigated theoretically the electronic stopping of protons in different solid forms of carbon: glassy, amorphous, graphite, diamond and C60-fullerite. The energy loss is described within the dielectric formalism and the target properties are modelled by a sum of Mennin-type energy loss functions. For each allotropic carbon form, we observe remarkable differences in the stopping cross section and in the energy loss straggling at proton velocities around and lower than that corresponding to the maximum in the energy loss. A comparison of our results with available experimental data shows a reasonably good agreement.

Electron beam deflection by a dielectric wedge

Abstract The image force felt by a swift electron beam travelling parallel to and just outside a non-planar dielectric wedge has been calculated within the framework of the classical dielectric theory of charged particles interacting with solids. This force is evaluated for different wedge sharpenesses and as a function of the beam energy and the distance from the electron beam to the dielectric surface. Our results suggest that this image force does not produce any appreciable electron beam deflection in practical electron microscopy situations.

Laser effects on proton energy loss in metals

Abstract We study the influence of a strong laser field on the stopping power and the inverse mean free path of protons moving in a degenerate electron gas. The energy-loss function is derived by means of a semiclassical approximation for the laser electromagnetic field, and the random-phase-approximation formalism is used taking into account the laser effects. The contributions to the energy losses due to plasmon and electron—hole excitations are discussed in terms of photon absorption or emission processes. These effects are analyzed as a function of the proton velocity and for different frequencies and intensities of the laser field.

Ripplon interaction between two liquid surfaces

Abstract The interaction between two liquid surfaces plays a central role in aerosol microphysics and liquid-drop aggregation phenomena. We study the ripplon (quantized capillary-tension waves) contribution to the interaction energy between two parallel planar liquid surfaces. For 4 He and separations between both liquid surfaces ≳10 A, the effect of ripplon excitation is negligible (smaller than 10 −3 ) compared with the van der Waals energy corresponding to two flat liquid 4 He surfaces. At smaller separation distances, the ripplon contribution to the interaction energy can no longer be considered as a perturbation and it should be included in any detailed analysis of liquid-liquid interactions.

Reflection of electromagnetic waves from rough waveguides

The reflection coefficient of a section of randomly rough waveguide is calculated using a coordinate transformation developed by A.K. Mallick and G.S. Sanyal (ibid., vol.26, no.4, p.243-9, 1978). A perturbed analysis which assumes that the amplitude of the roughness is small compared to the average width of the waveguide is performed. A drastic difference at long wavelengths between TEM on the one hand and TE and TM on the other has been found. >

Evolution of an electron beam travelling parallel to a uniformly charged surface

The authors discuss the behaviour of an electron beam running parallel to the flat surface of a metal or dielectric.

Interaction of a Charged Particle With a Semi Infinite Non Polar Dielectric Liquid

We investigate the classical interaction between a charged particle and a semi-infinite non-polar dielectric liquid. The classical results, in the long-distance regime, agree with a previous quantum-mechanical approach [1], which was used to describe the energy loss of an ion travelling parallel to the liquid surface (see also ref.[2]). The results in the (non-linear) short-distance regime provide information that was not available in the linearized quantum-mechanical calculations of the energy loss.