Apparent optical properties

The diffuse attenuation coefficient (K ) is one of several apparent optical properties (AOPs) of natural waters described by Preisendorfer [25]. Unlike inherent optical properties (lOPs) described below, AOP s depend on the quality of incident light as well as the optical qualities of the water. In spite of this apparent limitation (and in part because the differences between AOP s and lOP s were said to be small in many instances [26]), a case was argued for the standard use of to characterize natural waters for purposes of optical comparisons and bio-optical models [27,28]. Gordon [17,29] provided a practical means to adjust measurements to remove much of its dependence on the ambient light field. In particular, Gordon [17] established that, after adjustment (described below), averaged from surface to Zio% is proportional to the summed concentrations of constituent optical compounds. 

As we mentioned above, metal deposition on semiconductor electrodes usually starts with three-dimensional nucleation, which leads to discontinuous (clustered) overlayers. Such films have apparent optical properties which can be distinctly difierent from those of the metal clusters proper and which are determined also by the refractive index of the embedding medium (in our case, the electrolyte), the shape of the particles, and their volume fraction (filling factor fm). According to the Maxwell-Garnett theory, for spherical particles the optical response is ... 

The related copolymer 94, synthesized in the 1980s by Feast et al. [144], presents a rare example of a PPV-containing phenyl substituents on the vinylene unit. Apparently, the steric hindrance caused by phenyl substituents in 94 is not dramatic, and the optical properties of 94 are similar to those of other PPVs (green emission, APL AEL 530 nm). An internal QE of up to 1% was reported with multilayer 94-based PLEDs containing PPV 1 and PVK as HTL [145]. 

The driving force in polymer synthesis is the search for new polymers with improved properties to replace other materials of construction. Polymers are lightweight and can be processed easily and economically into a wide range of shapes and forms. The major synthetic efforts at present are aimed at polymers with high temperature, liquid crystal, conducting, and nonlinear optical properties [Maier et al., 2001 Sillion, 1999]. There is an interrelationship between these efforts as will become apparent. 

Rare earth doped alkali sulphates are of interest because of their optical properties. EPR spectra of y-irradiated Ce and Ce-U doped KjNa(S04)2 exhibited signals characteristic of a S04T SOjT radical pair.34 The dipolar splitting (32 G) corresponds to r = 9.8 A. The radical pairs create deep traps, apparently assisted by dopants. 

The importance of the graft handle on a 62/38 butadiene-methyl methacrylate rubber can be illustrated by its effect on the optical properties of the polyblend. From Table II it can be seen that the reduction in percent haze is dramatic for an increase of methyl methacrylate graft from 0 to 27% by weight, while there is no apparent change in the light transmission. The blend resin in this polyblend system was an 88-12 methyl methacrylate-styrene copolymer, and the total resin to backbone rubber ratio was kept at 2.5-1.0. The measured refractive indices are included for each component (the graft rubber and the blend resin). The difference in refractive index amounts to no more than 0.004 unit for any of the components. 

From these considerations it is apparent that PL in 71-Si is very sensitive to the chemistry of 71-Si production and treatment. Crystalline-Si wires, c-Si spherites, and amorphous Si (a-Si) material, or any combination of them, may be formed in a given sample. The 71-Si layers thus formed may be far from uniform, which adds to the difficulties in analyzing their optical properties. Other light emitting species may also be formed on the surfaces of the anodized and otherwise chemically treated Si. 

The apparent correlation between optical properties and such processes as clarification, decolorization, and crystallization is deceptive. In each case, complete quantitative evaluation must depend on the actual physical and chemical properties of the sugar colorant, and this information is, for the most part, lacking. 

Since only absorbed light can initiate photo transformations, it may be expected that samples of different optical properties show different photoproduction rates. For comparative purposes, the rates are thus usually absorbance-normafized. However, the inconsistency when comparing results from different studies is not resolved by such normalization and the variabifity of normafized rates exceeds an order of magnitude (Table 10.1). An attempt to find a correlation between available bulk characteristics (DON, DOC, pH, absorbance) and irradiation effects proved unsuccessful (Grzybowski, 2003). Additional confusion is introduced by reports on lack of ammonium release and even its removal during irradiation, observed in apparently similar samples (Table 10.1). 

Molecular nonlinear optics is the description of the change of the molecular optical properties by the presence of an intense light field. Since light either can be considered a classical electromagnetic wave or as a stream of photons, we may describe the interaction between light and matter in two apparently different ways, and we will start by considering how linear and nonlinear optical phenomena can be described in these two frameworks. 

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