Internal color conversion

Figure 9-4. Color conversion (a) shows the components needed for external color conversion, (b) for internal color conversion - lop riglu enlarged view of the emission layer which consists of a matrix and color-converting dopaiuls (black dots).

An efficient internal color-conversion technique will only occur if the polymers in the blend are only weakly phase separated. Otherwise, the various polymers in the blend behave similar to independent parallel diodes and hence a strongly voltage-dependent emission color will be observed.131,137... 

The internal color conversion in the m-LPPP PPDB blend can also be used to realize a stable white EL emission, which could be applied to realize a multicolor display according to the method in Sec. 8.2 or it could be used as backlight (e.g., for LCDs).137 140... 

Blue Large-Area EL Devices Covered with Filters and Appropriate Dye Layers That Convert the Blue EL Emission into the Required Emission Color. One of the most promising methods for the production of flat color screens is the use of blue PLEDs covered with dye layers to convert the EL emission into the RGB colors and, if necessary, with filters to purify the emission light [171-174] (see Fig. 30.20). In principle, the internal quantum efficiency of this technique for color conversion from blue into any other emission color can approach 100%. 

Fig. 48. Mean error for the simulation of the NOx conversion at steady-state and constant urea dosing conditions as a function of exhausts mass flow and catalyst inlet temperature. Reprinted with permission from SAE Paper 2005-01-0965 2005 SAE International (see Plate 6 in Color Plate Section at the end of this book).

All excited molecules will not undergo conversion to the metastable colored form, so that will generally be less than unity. Competing deactivating processes for the excited molecules include fluorescence, phosphorescence, permanent chemical reaction and internal conversion processes in which the excitation energy ultimately appears as thermal energy in the system. 

Figure 20. Integrated signals Ei and 2 for OHBA (a), ODBA (b), and HAN (c) plotted as a function of the time delay at the indicated excitation wavelength. Note the change in ordinate time scales. Signal Ei always followed the laser cross-correlation, indicating a rapid proton transfer reaction. The decay of signal 2 was fitted via single exponential decay, yielding the time constant for internal conversion of the Si keto state in each molecule. See color insert.

Figure 29.1 (a) Scheme of two-color fluorescence dip spectroscopy. The pump beam excites a molecule from the ground state (S0) to the S i state. Then, the erase beam further excites the St molecule to a higher excited state, S . Due to various relaxation processes from S states, such as internal conversion to the ground state,... 

Stoichiometric Oxidation of Lignin Model Compounds with Cobalt till) Acetate. In a typical procedure, a solution of DMMP (6.8 mg, 0.018 mmol) and cobalt (III) acetate (84.3%, 10.5 mg, 0.037 mmol) in 18 mL of glacial acetic acid was heated to reflux in 20 min with stirring. One hour later, the color turned from greenish black to pink. The solution was cooled to room temperature and veratrole (10.2 mg, 0.074 mmol) was added as an internal standard for HPLC analysis. A 67% selectivity to DMB at 99% conversion of DMMP was obtained. For reactions where cobalt(III) acetate still remained, an aqueous solution of ferrous sulfate was added dropwise until the color of the solution turned from green to pink then veratrole was added as internal standard. 

The AOS composition and quality are also linked to the structure and characteristics of the processed AO, particularly, the content of parafQns and internal isomer are the feedstock characteristics that adversely affect the completeness of AO to AOS conversion as well as the composition and color of the final product. 

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