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We present expressions for the resonant magnetic X-ray scattering (XRMS) by surfaces possessing roughness and analyze both the structural and magnetic roughness of a surface, as well as their correlation. We demonstrate that the leading contribution to the difference (DI) in the diffuse scattering between left- and right-circularly polarized light for a rough surface vanishes unless the structural and magnetic roughnesses are correlated, to leading order in the magnetization. The effects of magnetic domain structure and magnetic dead layers on the surface scattering are also discussed.

We report on the electronic properties of straight, 1.6 nm wide, silicene nanoribbons on Ag(110), arranged in a one-dimensional grating with a pitch of 2 nm, whose high-resolution scanning tunneling microscopy images reveal a honeycomb geometry. Angle-resolved photoemission shows quantum confined electronic states of one-dimensional character. The silicon band dispersion along the direction of the nanoribbons suggests a behavior analogous to the Dirac cones of graphene on different substrates.

Combined experiments on the aerosol properties were carried out with a solar aureolemeter, a Sun photometer, three aerosol cascade impactors, and the satellite advanced very high resolution radiometer data, in Cagliari and Carloforte, southern Sardinia, in May and June 1994. The experimental data of the aureolemeter, which operates in the wavelength range from the UV to the near-IR, are analyzed in this paper. The equivalent refractive index of the aerosol particles and the equivalent ground albedo are derived with the inversion library method. With the equivalent refractive index and the equivalent ground albedo, the optical properties of the aerosols, such as the size distribution, the optical thickness, and the single-scattering phase function are retrieved by an updated code, which employs a radiative intensity transfer algorithm and a nonlinear iterative inversion procedure. The columnar aerosols detected in this region have a trimodal size distribution with the volume mode radii located at about 0.15, 0.5, and 2.0 μm they present the typical maritime aerosol characteristics. The behavior of the aerosol optical thickness is described through its variations in 2 entire days. From this experiment we found that for the measurement of the diffuse solar radiation, three operational wavelengths in the UV, the visible, and the near-IR are sufficient to obtain satisfactory information on the aerosol optical properties in the spectral range covered by these wavelengths.

Dewfall and evapotranspiration have been measured with a weighable lysimeter and computed through the energy balance equation, during day and nighttime; the Kazanskiy-Monin nomograph has been used for parameterizing the air sensible heat flux. The experimental data have been taken on a flat lawn, starting after an irrigation. The results show that the values of the computed mean net water flux are always significant, that is, their signs are always unambiguous. There is a general good agreement between derived and measured water fluxes, and a good coincidence between derived and computed dew onset, dew ending and dew duration.

The latent heat flux has been determined during a fog situation by using a method based on the surface heat balance equation and a parameterization of the sensible heat flux. The computed values of the latent heat flux show that it is connected with changes in fog density.

Measurements of the direct solar and diffuse sky irradiances are used for deriving optical and physical features of the atmospheric aerosols: optical depth, size distribution, and complex refractive index. Sky irradiance is measured by means of a sky-radiometer (aureolemeter), which consists essentially of a photometer with annexed interferential filters for the selection of the wavelengths at which to operate, and a pointing system. The device used in the authors' research program, manufactured by the Japanese Company Prede (Tokyo), operates at the following wavelengths: 0.315, 0.400, 0.500, 0.870, 0.940 and 1.040 /spl mu/m. Measurements are undertaken in the two following different ways. Almucantar: pointing along a conical surface with the same zenith angle of the Sun. Principal plane, the instrument aims the sky along a plane with the same azimuth angle of the Sun. The two quantities considered in their scheme of data elaboration are the direct solar irradiance V and the ratio R between the diffuse and the direct irradiance.