Surface complexation models particle morphology

According to this simple model, the Agl actually forms at the surface and not in the core at all. The Agl phase that emerges onto the external silica surface grows by spherical diffusion in the bulk solution, where the I2 concentration is much higher, and diffusion is unimpeded. This may explain the hemispherical particle shape adopted by many of the Agl particles. It is apparent that such complex morphology changes could not have been predicted from the spectroscopic data shown in Figure 51.17 alone. 

For irregular isolated particles, numerical methods can be used to calculate the scattering efficiency. However, the SERS effect generally involves complex morphological substrates, such as electrochemicaUy roughened surfaces. In this case, collective effects between the particles play an important role in the SERS process, and the single particle models alluded to above are not very appropriate to simulate the scattering effect. 

The (i-band center model has been used extensively to describe experimentally measured catalytic activities, as a descriptor of catalyst behavior. Most computations have been performed on flat surfaces or surfaces with steps and kinks [7, 24,46 9]. The electronic stmcture of nanoparticles is expected to be deeply affected by the characteristic particle size and morphology. Particle size is therefore a critical parameter. The surface science studies that involve the reactions on a uniform single crystal surfaces and introduce the complexity characteristic to real nanoparticles by involving the defects, kinks, and steps in the models may not be sufficient to model the catalytic behavior at nanoscale. Such model does not take into account an inherent particle property sensitively dependent on structural parameters such as the particle size, strain, and local surface morphology. 

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