Relaxation thin films

Inner shell excitations of monothiophene in the compressed and relaxed thin film phase on Pt(]]l) (compare Section 3.1) as well as in the gas and solid... 

Available results indicate that partial relaxation in fairly thin films does leave them in reasonably uniform states of strain, and therefore must largely be interfacial. The solid points in fig. 7, other than those for films unrelaxed on Lu and Y, actually were taken from partially relaxed thin films (cf fig. 4). The fact that they conform accurately to the surface defined by unrelaxed systems indicated that their state of strain remains frozen at the part-relaxed value specified by the location of the points along the e-axis. Thus, they approximate epitaxial crystals but with modified interfacial registry. 

Physical Properties. Raman spectroscopy is an excellent tool for investigating stress and strain in many different materials (see Materlals reliability). Lattice strain distribution measurements in siUcon are a classic case. More recent examples of this include the characterization of thin films (56), and measurements of stress and relaxation in silicon—germanium layers (57). 

Another largely unexplored area is the change of dynamics due to the influence of the surface. The dynamic behavior of a latex suspension as a model system for Brownian particles is determined by photon correlation spectroscopy in evanescent wave geometry [130] and reported to differ strongly from the bulk. Little information is available on surface motion and relaxation phenomena of polymers [10, 131]. The softening at the surface of polymer thin films is measured by a mechanical nano-indentation technique [132], where the applied force and the path during the penetration of a thin needle into the surface is carefully determined. Thus the structure, conformation and dynamics of polymer molecules at the free surface is still very much unexplored and only few specific examples have been reported in the literature. 

Liquid lubricant confined in molecularly thin films would experience dramatic changes in its physical properties, such as increased viscosity, slow relaxation, and solidihcation. Progress in studies of thin film rheology has greatly improved our understanding of boundary lubrication, which is the subject to be discussed in this section and in the next. 

The solidihed layer yields and returns to the liquid phase if the shear stress excesses the critical value, which initiates the sliding. When the stress is relaxed as a result of slip, the solid phase resumes again. The periodic transition between the solid and liquid states has been interpreted in the literature as a major cause of the stick-slip motion in lubricated sliding. Understanding the stick-slip and static friction in terms of solid-liquid transitions in thin films makes a re-... 

An intense femtosecond laser spectroscopy-based research focusing on the fast relaxation processes of excited electrons in nanoparticles has started in the past decade. The electron dynamics and non-linear optical properties of nanoparticles in colloidal solutions [1], thin films [2] and glasses [3] have been studied in the femto- and picosecond time scales. Most work has been done with noble metal nanoparticles Au, Ag and Cu, providing information about the electron-electron and electron-phonon coupling [4] or coherent phenomenon [5], A large surface-to-volume ratio of the particle gives a possibility to investigate the surface/interface processes. 

Thin film electrodes have made feasible thermal jump kinetic measurements of extremely fast electrode reactions [26], by illuminating a thin electrode film by a very rapid laser pulse and monitoring the relaxation process on a nanosecond time scale. Thin films of silver have also been deposited on electrode materials such as carbon to enable surface-enhanced Raman spectroscopic investigation of surface-bound species [27]. 

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