Quantum yield, calculation

From the point of view of quantum yields calculation, photo-Fries rearrangement, including phenol and products formation, represents a photoreaction (expressed by Eq. 3) in which all products absorb intensively in the absorption region of the starting phenyl ester A. 

This method of quantum yields calculation was verified in more detail in studying the photorearrangement of 4-methylphenyl benzoate (60) (in ethanol with 253.7 nm).71 The quantum yield of ester decrease, Additional examples are calculations of the photorearrangements of poly-4-benzoyloxystyrene (in dioxane with 253.7 nm) (cpA = 0.082, methyl-phenyl acrylate ([Pg.138]

The very high limiting quantum yield calculated for the DCA-sensitized photooxygenation of 54 ( = 23.8) [115], together with the cyclic voltammetric spectra (Fig. 2a, b) recorded under inert and/or oxygen atmosphere [146], strongly support the following chain electron-transfer mechanism (Scheme 9). 

Primary quantum yields calculated by expressions (33) and (34) at various wavelengths, on the basis of the experimental results of Blacet and BelP" are listed in Table 32. In spite of the considerable disagreement between the values calculated by the two expressions, an increase in (j) with increasing frequency is obvious. 

The reaction reversibility stipulated by the sepulchrate [Co(sep)] + cation stability reduces the quantum yield (calculated from the decrease in the initial compoimd concentration) compared with nonmacrocyclic [Co(NH3)6] and [Co(en)3] + cations. The

values obtained from CO2 production retain the same order. 

The quantum yield calculated from laser data for solvated electron production by Aldrich HSX excited at 355 nm was extrapolated to a day averaged surface steady state concentration of solvated electron n sunlit waters. In direct sunlight an average rate of 1.62 X 10 photons per second Impinging on a square centimeter of surface water was calculated from solar photon fluxes (32-33). Using absorptlvltles of HS from 299 to 800 nm (with an O.D. of 0.1 at 355 nm) and a solvated electron production quantum yield of 0.014 (16), a rate of 3.50 x 10 moles of solvated electrons produced per second was calculated. Based on a lifetime of 0.25 microseconds for solvated electrons In air saturated natural waters, the surface steady state concentration the top coble centimeter of water was calculated to be about 10 M. 

Wavelength Sensitivity of Quantum Yields Calculated from Cut-on Filter Technique... 

As for the temperature dependence of the photolytic quantum yields of CH3COCH3, the total quantum yields increase with temperature in the wavelength region shorter than 295 nm, while they decrease with temperature in the wavelength region longer than 295 nm. NASA/JPL Evaluation No. 17 (Sander et al. 2011) gives the approximation formula of the quantum yields for the pressure and the temperature dependence based on Blitz et al. (2004). Table 4.17 shows the temperature dependent photolysis quantum yields and Fig. 4.21 depicts the photolytic quantum yields calculated by the approximation compared with experimental values (Blitz et al. 2004). 

Table 10.6 shows the quantum yields calculated from the equation 10.69. 

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