Light intensity dependence

Fig.6 Light intensity dependence of the induction period ( ) and the polymerization rate (A) of a UV curable PUA film.

These differences in the light intensity dependence of the decreasing rales between dry conditions and 50% relative humidity indicate that active species other than 02 and Cl are involved in the photochemical reaction in the presence of water vapor. Since the OH radical can be produced by the reactions of C2 and/or h+ with H20 and/or OH- groups on the surface, OH radicals may become the main contributor to TCE or PCE degradation under humid conditions. This assumption seems reasonable considering the relative magnitude in the reaction rates of OH with TCE and PCE in the gas-phase mentioned above. 

The stabilization of illuminated n-type III-V semiconductor electrodes through competing hole capture by reducing agents added to the aqueous solution has been studied as a function of concentration and of the light intensity. The main result concerns the observed light-intensity dependence. From a kinetic analysis of the stabilization process, it follows that two types of reaction mechanisms can be held responsible for the observed kinetics. 

Figure 4. Light intensity dependence of the photoreduction current of anthra-quinone in acetonitrile. An anodic wave grows in at about 0.0 V (vs. SSCE) with...

IET serves as a theoretical basis not only for fluorescence and photochemistry but also for photoconductivity and for electrochemiluminescence initiated by charge injection from electrodes. These and other related phenomena are considered. The kinetics of luminescence induced by pulse and stationary excitation is elucidated as well as the light intensity dependence of the fluorescence and photocurrent. The variety and complexity of applications proves that IET is a universal key for multichannel reactions in solutions, most of which are inaccessible to conventional (Markovian) chemical kinetics. 

P. Schilinsky, C. Waldauf, J. Hauch, C.J. Brabec, Simulation of light intensity dependent current characteristics of polymer solar cells, J. Appl. Phys. 95 (2004) 2816. 

Experimentally this process can be observed as a quadratic light intensity dependent photoconduction [177—180] and external photoemission of electrons [181-183] or fluorescence quenching [148,155,184-186]. 

MEH-CN-PPV, (b) hetero-junction solar cell, and (c) the light intensity dependence of the cell current and voltage. Reprinted with permission from Nature, Granstrom et al. (1998). Copyright 1998 Macmillan Magazines Limited. 

Fill factor for DSC are hmited in general by series resistance losses, light-intensity dependent recombination, nonideal dark diode currents and, in some cases, shunt resistance losses. 

As an empty surface state may be associated with Xj (see also further), reaction (23) electronically amounts to the filling of such a state by Y. A slightly modified form of this mechanism has been proposed by Gerischer and LUbke [51] to account for light-intensity-dependent stabilization kinetics. 

The a values were determined under various experimental conditions. At 3650 A, a was found to depend on the biacetyl pressure the reported values were between 0.2 and 0.3 at low pressure, and approached 0.5 at high pressure. (There was also a light intensity dependence observed in the low pressure range.) At room temperature, in the wavelength region 3650-2654 A, a increased with increasing frequency of radiation. At 3130, 2700 and 2654 A, the values were around 0.35, 0.5 and 0.6, respectively. 

Fig. 43 Chemical structure of MEH-PPV and CN-PPV left) as well as the monochromatic (430 nm) light intensity dependence of the I-V characteristics of MEH-PPV CN-PPV blend polymer solar cells right). (Reprinted with permission from [28], 1995, American Institute of Physics)...

Fig. 44 Light intensity dependence of short circuit photocurrent (filled circles) and open circuit voltage of laminated POPT (MEH-)CN-PPV diffuse bilayer polymer solar cells. The scaling factor of the current calculates as 1.02. (Reprinted with permission from [32], 1998, Macmillan Publishers Ltd)...

Roster LJA, Mihailetchi VD, Ramaker R, Blom PWM (2005) Light intensity dependence of open-circuit voltage of polymer fullerene solar cells. Appl Phys Lett 86 123509... 

From this model one expects a light-intensity-dependent steady state concentration of dissolved iron(II) in the photic zone of a natural-water system. What steady-state concentration can be reached depends on the pH, the content and the type of dissolved organic matter, and above all the crystallinity of the iron(III) hydroxide phase. 

For a population of n excited atoms, the emitted light intensity depends upon the number of atoms dn that return to the ground state during the interval of time dt (dn/dt = kn). Since n is proportional to the concentration of the element in the hot zone of the instrument, the emitted light intensity which varies as dn/dt, is itself proportional to the concentration ... 

A systematic study of the product distributions resulting on photolysis of diphenyl- and substituted diphenyliodonium cations as functions of both solvent and counterion was carried out by Timpe and Schikowsky [71]. Unlike the earlier results of Pappas, these authors found that, taking into consideration all organic products, quantum yields of the disappearance of iodonium cations and of formation of protic acid are within experimental error. Significantly, light intensity, /, dependence of the quantum yields was observed in this study. Timpe and Schikowsky s principal observations are summarized in Table 3. 

Falbel TG, Staehelin LA and Adams WW III (1994) Analysis of xanthophyll cycle carotenoids and chlorophyll fluorescence in light intensity-dependent chlorophyll-deficient mutants of wheat and barley. Photosynth Res 42 , 191-202... 

Fig. /. Light intensity dependence of the rate of excitation of the light harvesting system of the chloroplast and the rate of photosynthesis. Below the photosynthesis curve is the utilized light and above the curve is the (potentially damaging) excess.

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