The rates of reaction of OH with propyne, but-l-yne, but-2-yne, pent-l-yne and hex-l-yne have been measured directly by using a discharge-flow resonance-fluorescence technique over a range of temperatures from 253 to 343 K. The room-temperature rate coefficients-are compared with previous determinations; the new values for pent-l-yne and hex-l-yne fit into a general pattern of reactivity consistent with a mechanism involving initial electrophilic attack of OH at the triple bond. Similar trends are also presented for other series of reactions between radicals and unsaturated organic molecules. The temperature dependences of the rate constants for the OH-talkyne reactions are small or negative, suggesting that adduct formation is the initial step in the reaction mechanism.

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The temperature dependence of the three dimol emissions of oxygen 02(lAg) at 579,634 and 703 nm has been studied between 295 and 1500 K with a discharge-flow-shock-tube apparatus. The intensity increases with temperature and concentration as expected for these bimolecular processes, but there is a further increase which is attributed to the appearance of overlapping hot-band emissions from vibrationally excited molecules of OZ('Ag). For the 703 nm emission there is an additional contribution from hot bands of O2(*Zi).