Introducing reflection anisotropy spectroscopy (RAS) as a new probe for solid-liquid interfaces, we present results for the Au(110)/electrolyte interface which serves as a model system. We demonstrate that RAS is sensitive to surface phase transitions, step morphology, and electronic surface states. Using an empirical approach, the RA spectra are reproduced and features are identified which reflect the known character of the bias voltage driven (2x1) to (1x1) phase transition. RAS is established as an experimental technique to probe the electronic structure of solid-liquid interfaces in real time to study a wide range of interface properties.

We report the first measurements of the reflectance anisotropy (RA) spectrum from a body-centred cubic transition metal surface, W(110), and provide a detailed interpretation based upon surface electronic structure calculations. The RA profile exhibits a pronounced resonance feature centred at 3.4 eV which decreases upon oxygen adsorption, indicating a surface effect. Calculating the surface dielectric function within a joint density of states approximation, we identify the important transitions: these are between occupied surface states with a large p-component to unoccupied d-states, with the RA arising from the different contributions of px and py states. These surface states have previously been measured using angle-resolved photoemission. The calculated resonance feature occurs at an energy of 2.9 eV, and the difference with experiment is attributed to self-energy effects.

Articles you may be interested inTheoretical signal-to-noise ratio and spatial resolution dependence on the magnetic field strength for hyperpolarized noble gas magnetic resonance imaging of human lungs Med.Molecular diffusion during the application of magnetic field gradients can distort magnetic resonance images. A systematic characterization of these distortions in one dimension was performed using highly spin-polarized xenon gas. By varying the strength of the applied gradient and the geometric dimension of the sample, the evolution of these image distortions between the regimes of strong and weak diffusion was observed. These results are compared with numerical simulations. By directly measuring the displacement distribution of the polarized xenon atoms, it is shown that in the weak-diffusion regime the image distortions originate from the restricted diffusive motion near the sample boundaries, in agreement with previous theoretical work. Additionally, it is shown that the effects of diffusion can be utilized to enhance the contrast between the boundaries and bulk in the images of polarized gas samples, and thus may be exploited as a means of boundary detection in such systems.