Experiments are described in which double-beam absorption measurements are made at high spectral resolution (better than 0.05A in the visible and near ultraviolet) at an accurate sequence of time intervals as short as 200 μsec. This is accomplished with a high-resolution monochromator and dual-photomultiplier detector using a stroboscopic xenon flash source. Signals representing the absorption ratios are recorded on magnetic tape and read out with a digital integrator.
A quantitative test of this procedure was made by observing the iodine recombination reaction following flash photolysis. The accuracy of the results compares favorably with previous measurements which have used spectral bandwidths a thousand times broader. The use of this method for measuring rates of free-radical reactions is described using observations of NH2 radicals as an illustration.
© 1961 Optical Society of AmericaFull Article | PDF Article
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