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IX-C-9. Estimated acrolein photodissociation coefficients as a function of solar zenith angle. The cross sections and quantum yield estimates used in the calculation are as described in the text. The calculation was made for a cloudless sky, 0.5 km elevation, and a vertical ozone column of 350 DU.

IX-C-I I. Estimated methacrolein photodissodation coefficients at 0.5 km altitude as a function of solar zenith angle, ealeulated using the measured a values and the approximate methacrolein quantum yield estimates given in table IX-C-4. The solid curve represents the total y the error bars shown are assigned arbitrarily by the present authors to indicate an unidentified yet significant uncertainty in the measurement.

IX-C-IS. Approximate values of the photolysis frequencies as a function of solar zenith angle for cis- and rrani-4-oxo-2-pentenal. Estimates have been calculated for a cloud-free lower troposphere assuming totai 1 and an overhead ozone column of 350 DU.

IX-C-S. Comparison of the absorption spectra of acrolein .

IX-D-1. Absorption spectra fca- some simple ketones data from Martinez et al. .

IX-D-14. Quantum yields of C2H4 in 2-pentanone photolysis as a fnnction of added 1,3-butadiene or 1,3-pentadiene. Data from Wettack and Noyes wavelength, 313nm temperature, 25 C.

IX-D-15. Effect of added O2 on the quantum yields of products .

IX-D-16. Approximate photolysis frequencies for primary processes in 2-pentanone versus solar zenith angle CH3CH2CH2C. Case A assumes that all processes are quenched in air to the limiting values observed for 2,3-butanedione and diene quenching case B assumes quenching as in A but additional quenching as observed for acetone-air photolysis. Data were calculated for a cloudless day in the lower troposphere with an overhead ozone column of 350 DU.

IX-D-17. Approximate 7-values for primary process .

IX-D-18. Comparison of absorption spectra of some branched chain ketones .

IX-D-19. . The Norrish type-II process can be represented in this case as

IX-D-2. Semilog plot of the Stern-Vohner constants . The trend line is the least-squares fit to the data excluding the most divergent points at l X 0.00403 and 0.00303 nm

IX-D-3. Experimental determinations of the quantum yields of acetone photodecomposition as a function of wavelength for photolyses in air at 760Torr and 298 K. The dashed gray curves define an envelope that describes the range of possible values. Values from the two dashed curves were used in estimating the possible range of photolysis constants shown in figure IX-D-6. Authors of the current study recommend use of the values given by the short-dashed line. The maximum values are also given in table IX-D-2.

IX-D-4. Plot of the estimates of j i from photolysis of acetone in air at 760Torr versus 1 9. for data at long wavelengths. The least-squares lines are fits and are shown for each individual data set and the combined data. The y-axis intercepts are

IX-D-6. Stern-Volmer plot of l I co versus pressure of added nitrogen gas. Experiments were all performed using 248 lun excitation of acetone. Measurements of OchjCO reported by Rajakumar et al. were converted to equivalent values of t co using the expression, 4 co bcH3 - 1

IX-D-7. Plot of the estimated photolysis frequencies for acetone photodecomposition for a cloudless day within the lower troposphere at 760Torr and 298 K. The black solid and dashed curves represent the maximum and minimum -values, respectively, for the total photodecomposition process in acetone are very near zero.

IX-D-8a. Approximate percentage decrease in the total -values for acetone for data presented in figure VII-C-6a for overhead ozone columns of 300-350 and 350-400 Dobson

IX-D-8b. Estimated percentage decrease in the -values for the primary processes in formaldehyde photodissociation in the lower troposphere with overhead ozone column of 300-350 .

IX-D-9. Comparison of the spectraly-values for acetone for an overhead ozone column of 350 DU.

IX-D-IO. Approximate photolysis frequencies for the photodecomposition of 2-butanone as a funetion of solar zenith angle for a eloudless day in the lower troposphere with an overhead ozone eolumn of 350 DU.

IX-D-S. Plot of experimental estimates of process in acetone-air mixture photolysis as a function of wavelength. The dashed trend line is recommended for photolyses at low pressures of the upper troposphere the solid trend Une is recommended for photolyses at 1 atm.

IX-E-1 shows the approximate cross sections for cyclobutanone . Note in the figure that there is much less shift of the absorption band from that of acetone than is observed for cyclopropanone. The tabular listing of the cross sections is given in table IX-E-2.

IX-E-12. Quantum yields of products versus wavelength for photodecomposition of cyclohexanone at 1 Torr pressure .

IX-E-13. The effect of pressure on the relative quantum yields of 1-pentene, cyclopentane, and 5-pentenal products from the photolysis of cyclohexanone .

IX-E-14. Comparison of the absorption spectra of ketene and methylketene with that of acetaldehyde. The actinic flux data are those measured at noon on June 19, 1998 near Boulder, CO.



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