Photoreduction of nitrogen trifluoride with controlled release of radicals

BACKGROUND With the rapid growth of the semiconductor and thin film transistor liquid crystal display manufacturing industries, large quantities of the potent greenhouse gas nitrogen trifluoride ( NF 3 ) is in demand. But perfluorocarbons are very stable compounds because of their molecular structures. Therefore, in the atmosphere, NF 3 is difficult to oxidize by O 3 , NO , NO 2 , and OH radicals, except by excited oxygen atoms O( 1 D ) that can react with it to form NF 2 or other products. In this study the possible degradation process of NF 3 in the ‘controlled release of radicals’ reactor is discussed.RESULTS Under the conditions of 5 mmHg partial pressure of NF 3 and 600 mmHg total pressure with buffer gas of argon, NF 3 was photodegraded in an in situ reactor with a ‘controlled release of radicals’ system. The results indicated that reductive double bonds and allyl radicals, slowly released from polyisoprene irradiated by a UV lamp emitting 185 and 253.7 nm of light, could contribute to the NF 3 degradation in the CRR system. The NF 3 degradation efficiency, significantly affected by O 2 and almost independent of N 2 , reached 96% with a kinetic rate constant k ≈ 1.77 × 10 −4 s −1 after 300 min of ultraviolet irradiation.CONCLUSION According to the experimental results, a potential way of continuous photoreduction of NF 3 was found , since excited double bonds and allyl radicals are consequently released by irradiating the surface of the polymer matrix. The considerable degradation reaction constant of NF 3 and no fluoride byproducts in gas make it possible for industry application. © 2013 Society of Chemical Industry