The quantum yield (QY) of the iodide/iodate chemical actinometer (0.6 M KI/ 0.1 M K103) was determinedirradiation between 214 run and 330 mu. The photoproduct, triiodide, was determined flum the increase iabsorbance at 352 run, which together with a concomitant measurement of the UV fluence enabled the QY tocalculated. The QY at 254 mn was determined to be 0.75 0.02 when calibration was carried out against a NIStraceable radiometer or photometric device. At wavelengths below 254 mn, the QY increased slightly leveling oat -0.80 +/- 0.05, while above 254 mu the QY decreases linearly with wavelength reaching a value of 0.30 at 28mn. In addition, the QY was measured at different iodide concentrations. There is a slight decrease in QY goinfrom 0.6 to 0. 1 5 M KI, while below 0. 1 5 M KI the QY drops off sharply, decreasing to 0.23 by 0.006 MCalibration of the QY was also done using potassium ferrioxalate actinometry to measure the irradiance. Thesresults showed a 20% reduction in QY between 240 run and 280 mn as compared with radiometry. Thdiscrepancy suggests that the QY of the ferrioxalate actinometer in this region of the spectrum neereexamination.
Citation: Photochemistry and Photobiology
Issue: No. 2
Pub Type: Journals
actinometry, iodide/iodate, photochemistry, quantum yield, UV