Ferrioxalate Actinometer Research Articles

Ultraviolet Spectral Energy Distributions of Natural Sunlight and Accelerated Test Light Sources*

A contributory factor to the failure of correlation between outdoor and indoor photodecomposition tests is the difference in the ultraviolet spectral energy distributions of natural sunlight and the various indoor test sources which do not duplicate sunlight and differ widely among themselves.The ultraviolet spectral energy distributions of natural sunlight and of a variety of indoor exposure test sources have been measured. By use of a ferrioxalate actinometer, the measurements have been put on an absolute basis permitting the intercomparison of the sources. The xenon arc was found to be the best approximation of sunlight in the ultraviolet. For shorter-wavelength ultraviolet (below 3500 A), the combination of fluorescent Sunlamp and Blacklight lamps also approximated sunlight.

La Spécificité des Halogénations Atomiques VIII. La Mise Au Point D'Une Méthode Actinométrique

AbstractThe quantum yield of the gas phase photochlorination of C2Cl4 and C2Cl3H have been measured. The light intensity of a Hg vapour lamp transmitted by a filter has been measured with a potassium ferrioxalate actinometer. The spectral intensity distribution of the light was measured and corrections were applied for intensity loss and multiple reflexions. The quantum yield is given by Φ = Ia−1/2k(Cl2) with log k = –(1065 ± 8)/T + 3.941 ± 0.021 for the photochlorination of C2HCl3. Conditions are described which permit one to use this reaction as an actinometer for other photochlorinations, so as to avoid the corrections mentioned above and permitting one to use the approximation Ia = 2,303. Ioϵl(Cl2) even at high absorption (up to about 180 mm Cl2 with light of about 4300 A). The photochlorination of C2Cl4 has a somewhat more complexe mechanism and is therefore not very adequate for actinometry.