Rahn Ronald O, Stefan Mihaela I, Bolton James R, Goren Evan, Shaw Ping-Shine, Lykke Keith R
Department of Environmental Health, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Photochem Photobiol. 2003 Aug;78(2):146-52. doi: 10.1562/0031-8655(2003)078<0146:qyotic>2.0.co;2.
The quantum yield (QY) of the iodide-iodate chemical actinometer (0.6 M KI-0.1 M KIO3) was determined for irradiation between 214 and 330 nm. The photoproduct, triiodide, was determined from the increase in absorbance at 352 nm, which together with a concomitant measurement of the UV fluence enabled the QY to be calculated. The QY at 254 nm was determined to be 0.73 +/- 0.02 when calibration was carried out against a National Institute of Standards and Technology traceable radiometer or photometric device. At wavelengths below 254 nm the QY increased slightly, leveling off at -0.80 +/- 0.05, whereas above 254 nm the QY decreases linearly with wavelength, reaching a value of 0.30 at 284 nm. In addition, the QY was measured at different iodide concentrations. There is a slight decrease in QY going from 0.6 to 0.15 M KI, whereas below 0.15 M KI the QY drops off sharply, decreasing to 0.23 by 0.006 M KI. Calibration of the QY was also done using potassium ferrioxalate actinometry to measure the irradiance. These results showed a 20% reduction in QY between 240 and 280 nm as compared with radiometry. This discrepancy suggests that the QY of the ferrioxalate actinometer in this region of the spectrum needs reexamination.
测定了碘化物 - 碘酸盐化学光量计（0.6 M KI - 0.1 M KIO₃）在214至330 nm波长范围内的量子产率（QY）。通过352 nm处吸光度的增加来测定光产物三碘化物，结合紫外光通量的同步测量，可计算出量子产率。当使用可溯源至美国国家标准与技术研究院的辐射计或光度计进行校准时，254 nm处的量子产率测定为0.73±0.02。在波长低于254 nm时，量子产率略有增加，稳定在 -0.80±0.05，而在254 nm以上，量子产率随波长线性下降，在284 nm处达到0.30的值。此外，还在不同碘化物浓度下测量了量子产率。从0.6 M KI降至0.15 M KI时，量子产率略有下降，而在低于0.15 M KI时，量子产率急剧下降，到0.006 M KI时降至0.23。还使用草酸铁钾光量计测量辐照度对量子产率进行了校准。这些结果表明，与辐射测量法相比，在240至280 nm之间量子产率降低了20%。这种差异表明，在该光谱区域草酸铁光量计的量子产率需要重新审视。
