Surface optical properties

Many of the chemical and physical properties of mineral fillers are important in their application in thermoplastics. These include purity, specific gravity, hardness, electrical, thermal and optical properties, surface area, particle shape and size. The determination and importance of many of these has been covered in several reviews [65,66]. Only a brief coverage is given here for the less ambiguous properties such as specific gravity, hardness and standard thermal and optical properties, with most attention being concentrated on properties such as size and shape which have been found to give particular problems in measurement and interpretation. 

The two-volume set Properties and Behavior of Polymers offers over 40 self-contained articles written by prominent scholars from around the world. The articles provide comprehensive, up-to-date information on the physical properties of polymers and the resulting characteristics and behavior, including viscoelasticity, flammability, miscibility, optical properties, surface properties and more. 

Actual crystal planes tend to be incomplete and imperfect in many ways. Nonequilibrium surface stresses may be relieved by surface imperfections such as overgrowths, incomplete planes, steps, and dislocations (see below) as illustrated in Fig. VII-5 [98, 99]. The distribution of such features depends on the past history of the material, including the presence of adsorbing impurities [100]. Finally, for sufficiently small crystals (1-10 nm in dimension), quantum-mechanical effects may alter various physical (e.g., optical) properties [101]. 

There are a few other surface-sensitive characterization techniques that also rely on the use of lasers. For instance surface-plasmon resonance (SPR) measurements have been used to follow changes in surface optical properties as a fiinction of time as the sample is modified by, for instance, adsorption processes [ ]. SPR has proven usefiil to image adsorption patterns on surfaces as well [59]. 

As an indication of the types of infonnation gleaned from all-electron methods, we focus on one recent approach, the FLAPW method. It has been used to detennine the band stmcture and optical properties over a wide energy range for a variety of crystal stmctures and chemical compositions ranging from elementary metals [ ] to complex oxides [M], layered dichalcogenides [, and nanoporous semiconductors The k p fonnulation has also enabled calculation of the complex band stmcture of the A1 (100) surface... 

This section will outline the simplest models for the spectra of both metal and semiconductor nanocrystals. The work described here has illustrated that, in order to achieve quantitative agreement between theory and experiment, a more detailed view of the molecular character of clusters must be incoriDorated. The nature and bonding of the surface, in particular, is often of crucial importance in modelling nanocrystal optical properties. Wlrile this section addresses the linear optical properties of nanocrystals, both nonlinear optical properties and the photophysics of these systems are also of great interest. The reader is referred to the many excellent review articles for more in-depth discussions of these and other aspects of nanocrystal optical properties [147, 148, 149, 150, 151, 152, 153 and 1541. 

Optical Properties. Owing to the high crystallinity of HDPE, most thick-waHed articles made from HDPE resins are opaque. Significant surface roughness can also add to the opacity. Thin HDPE film, in contrast, is translucent, but its transparency is significantly lower than that of LDPE or LLDPE film. The ultraviolet transmission limit of HDPE is around 230 nm. 

Optical Properties. The index of refraction of a deposited material is sensitive to the film density. A lower index of refraction is found at less than bulk densities. The reflectance of a metallic surface is affected by the growth morphology of the film. 

STM and SFM are free from many of the artifacts that afflict other kinds of profilometers. Optical profilometers can experience complicated phase shifts when materials with different optical properties are encountered. The SFM is sensitive to topography oidy, independent of the optical properties of the surface. (STM may be sensitive to the optical properties of the material inasmuch as optical properties are related to electronic structure.) The tips of traditional stylus profilometers exert forces that can damage the surfaces of soft materials, whereas the force on SFM tips is many orders of magnitude lower. SFM can image even the tracks left by other stylus profilometers. 

Clouds cover roughly two-thirds of our earth s surface and play an important role in influencing global climate by affecting the radiation budget. Cirrus clouds are one example of a cloud type whose optical properties are not accurately known. Cirrus clouds form in the upper troposphere and are composed almost exclusively of non-spherical ice crystal particles. The impact of cloud coverage on dispersion of pollution in the atmosphere is an area of great concern and intensive study. 

The optical properties of tubular blown film depends greatly on the surface irregularities and the size of crystallites domain in film, which, in turn, are dependent on... 

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