This is not the result of an increase of V 0 (Fig. 3A) shifting only slightly from V 0 Ϸ 3 V at 320 K to V 0 Ϸ -2.5 V at 144 K. 19. It was assumed that V 0 , which is read directly from the transfer characteristics, can be taken as a rough estimate for V FB , that is, n ind S Ϸ C i /e(V g -V 0 ).

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We report ferromagnetic resonance experiments on Ga1−xMnxAs thin films. For the dc magnetic field perpendicular to the sample plane, we observe up to eight distinct resonances, which we attribute to spin wave modes. To account for the spacing of the resonances, we infer a linear gradient in the magnetic properties, which is ascribed to a linear variation of the uniaxial magnetic anisotropy with film thickness. Values of D=(1±0.4)×10−9 Oe cm2 for the spin stiffness and JMnMn≈1 meV for the exchange integral between Mn spins are obtained.

The aim of the present work is to provide a deeper understanding of gold catalysis for CO electrooxidation in alkaline media, through a combined electrochemical, spectroscopic, and DFT study. Voltammetric and spectroscopic measurements evidence that the amount of CO irreversibly adsorbed on gold increases as the adsorption potential becomes more negative (vs SHE). This explains why higher CO coverages can be achieved in more alkaline solutions, since the value of adsorption potential vs RHE becomes more negative vs SHE with increasing pH. On the other hand, the combination of FTIRRAS experiments and DFT calculations shows that the adsorption site of irreversibly adsorbed CO on Au(111) depends on the value of the adsorption potential. It is concluded that CO adsorption on top sites takes place at all studied potentials, and hollow and bridge sites also become occupied for adsorption potentials lower and higher than 0 V vs RHE, respectively. However, it should be noted that our DFT calculations give values of the CO binding energies that are not strong enough to explain CO irreversible adsorption. This may be partly attributed to the fact that OH coadsorption is not included in the calculations. Indeed, this work presents two experimental facts that suggest that CO adsorption on gold promotes the coadsorption of OH species: (i) CO irreversibly adsorbed on Au(111) and Au(100) leads to an unusual voltammetric feature, whose charge indicates the stabilization of one OH species per adsorbed CO species; (ii) the apparent transfer coefficient of this unusual state is close to unity, suggesting that it is due to a presumed structural transformation coupled to OH adsorption. Finally, the effect of the adsorption potential on the bulk CO electrooxidation is also studied. It is found that, on Au(111), an increased occupation of CO on multifold (hollow) sites seems to result in a less efficient catalysis. However, on Au(110), an increased coverage of CO on top sites does not produce any significant change in catalysis.