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By means of the new molecular modulation^method, the gas-phase absorption spectra of the peroxyl radical ClOO has been observed between 2300 and 2600 Á (ultraviolet) and between 1430 and 1460 cm-1 (infrared). This radical was produced by the photolysis of Cl2 in the presence of 02. The ultraviolet spectrum of the CIO radical was also observed, but its infrared spectrum could not be obtained by this method. By direct observation of these two intermediates, a detailed kinetic study was carried out, in which radical half-lives were inferred from observed phase shifts between the square-wave photolyzing light and the radical concentration. To enhance the weak signals from the low concentration radicals, the data were put in digital form and long-term averaging was carried out. The mechanism built up by previous workers was modified slightly to give a ten-step mechanism, which is in excellent agreement with observations. By combining other rate measurements, thermodynamic data, and the present results, seven out of the ten elementary rati; constants were evaluated, and a product-and-ratio of the other three was evaluated as one term. The absolute cross section for absorption of infrared and ultraviolet radiation by ClOO was determined.Porter and coworkers1-3 postulated the ClOO peroxy radical as a short-lived precursor to the CIO radical which they detected in the flash photolysis of chlorine:oxygen mixtures. On the basis of the very small temperature coefficient of CIO formation, Porter and Wright2•3 concluded that the only plausible reaction by which CIO could be formed is (1) G. Porter, Discussions Faraday Soc" 9, 60 (1950).

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Dimethylaminodifluorophosphine, (CH3)zNPFz (mp -W0), crystallizes with four formula units in an orthorhombic cell with a = 10.808 (12) A, b = 7.601 ( 7 ) A, and c = 6.259 (6) b a t -110'. A total of 458 photographically recorded and visually evaluated X-ray data were used to determine the structure, which has been refined to R = 0.069. A space group ambiguity was resolved in favor of Pnma following least-squares refinement in both Pnma and PnZia and consideration of the effect of a slight scaling error in the weakest observed reflections. The molecule possesses mirror symmetry with the planar P-K-C skeletofi lying in a crystallographic mirror plane. Bond lengths and standard deviations are P-N = 1.628 ( 5 ) , P-F = 1.610 (4), and C-N = 1.460 (9) and 1.485 (8) b.