自由基NH2與NO,NO2之反應動力學研究

Abstract

我們利用雷射光解/雷射誘發螢光法,探討在燃燒化學與大氣化學中有相當 重要地位的NH2自由基之兩個重要基元反應:NH2+NO及NH2+NO2.實驗結果所 得此二反應在20-90torr下,溫度分別為226K-573K及253K-461K間的反應速 率係數如下: NH2+NO->products k1=2.5*10^-12*exp(566/T) cm^3 molecule^-1 s^-1 NH2+NO2->products k2=1.2*10^-11*exp(336/T) cm^3 molecule^-1 s^-1於本套系統中,實驗所得之二級反應速率係數值, NH2+NO反應與已發表值相彷,顯示本實驗系統可以精確地進行自由基反應 的動力學研究.而反應NH2+ NO2之動力學研究結果則與已發表值有很大差 異.這兩個反應都觀察到負溫度效應與無壓力相依的現象. Amidogen radical(NH2) plays an important role in atmosphere chemistry and combustion chemistry. The absolute rate coeffcien- ts of the reactions of NH2+NO and NH2+NO2 have been determined using laser photolysis-laser induced fluorescence technique at 226K-573K and pressure 20-90 torr. The results are:(in units : cm^3 molecule^-1 s^-1) NH2+NO->products k1=2.5*10^-12*exp(566/T) NH2+NO2->products k2=1.2*10^-11* exp(336/T) k1 is in good agreement with previous measurements. The rate coeffcients of the NH2+NO2 reaction do not agree with the rep- orted results. Our results also show both two reactions are p- ressure independent and have negative temperature dependence.