TAILIEUCHUNG - MASS TRANSFER ADVANCED ASPECTS_2

Our knowledge of mass transfer processes has been extended and applied to various fields of science and engineering including industrial and manufacturing processes in recent years. Since mass transfer is a primordial phenomenon, it plays a key role in the scientific researches and fields of mechanical, energy, environmental, materials, bio, and chemical engineering. In this book, energetic authors provide present advances in scientific findings and technologies, and develop new theoretical models concerning mass transfer | Part 4 Advances in Materials Engineering Aspects 18 Light-Induced Surface Diffusion Tigran Vartanyan Sergey Przhibel skii Valerii Khromov and Nikita Leonov St. Petersburg State University of Information Technologies Mechanics and Optics Russian Federation 1. Introduction Surface diffusion of indigenous and or foreign atoms plays a key role in a number of physical and chemical processes. To name a few it is important in crystal growth and epitaxy heterogeneous catalysis nucleation and growth of supported nanoparticles and so on. Finding a reliable tool to control the surface diffusion processes is an attractive goal for many modern technologies. Optical photons being absorbed by the surface or by the species adsorbed onto it can alter the surface diffusion considerably. At lager intensities of illumination these alternations are mainly due to the temperature rise while at the lower intensities non-thermal mechanisms of light-induced surface diffusion are operative. The latter are the subjects of this chapter. The electronic excitation follows after the photon absorption and changes the forces exerted by the surface onto the adsorbed atoms. After a short period of time the energy of the photon is partitioned between the surface and the adsorbed atom. The excess energy obtained by the adsorbed atom results in the increased desorption rates from as well as diffusion rates over the surface. An inhomogeneous illumination of the surface leads to the inhomogeneous steady state distribution of the adsorbed atoms over the surface. The situation is similar to the Soret effect but require a special theoretical consideration that is presented in this chapter. An unexpected result of the theoretical analysis is that the spatial distribution of the surface number density of the adsorbed atoms is non monotone. There is a pronounced maximum of the surface number density of the adsorbed atoms at the boundary between the illuminated and the dark regions. The shapes of the supported .

• Cơ khí - Chế tạo máy
• Photometric Studies
• Cataclysmic Variables
• Non Magnetic
• UV Emission
• Spectral Synthesis
• Liquid Surface
• Mathematical Approaches
• Diffused reflectance
• Racah parameters
• Solid state displays
• Emission spectra
• Advanced materials and devices
• Genome Biology
• Differential equation models
• Parameter estimation
• Systems biology
• Insufficient performance
• Chemical Engineering
• mathematical modelling
• physical processes
• vehemently accelerating
• interfacial research
• theoretical approaches