采用激光光解 激光诱导荧光 (LP LIF)的方法 ,用 2 6 6nm激光光解CHBr3 分子产生CH自由基 ,再与N2 O继续反应作为NCO自由基的产生源 ,用 4 38.6nm激光将电子基态X 2 Πi(0 0 10 )的NCO激励到激发态A2 Σ+ (0 0 0 0 )上 ,通过检测激发态NCO时间分辨荧光信号 ,测得室温 (2 98K)下NCO(A2Σ+ )被烷烃类分子猝灭的实验结果 ,获得了A 2Σ+ (0 0 0 0 )态猝灭速率常数 .实验发现 ,随着烷烃分子中C -H键数增加 ,其猝灭截面也近线性增加 ,但随着分子体积增大 ,这种增加趋缓 . Using laser photoluminescence induced fluorescence (LP LIF) method, CHBr3 molecules were photodissociated with 266 nm laser to generate CH radicals and then reacted with N2 O as a source of NCO radicals. The electron ground state NCO (A2Σ +) is excited by the NCO of X 2 Πi (0 0 10) to the excited state A2Σ + (0 0 0 0). By detecting the time-resolved fluorescent signal of excited NCO, The quenching rate constants of A 2Σ + (0 0 0 0) state were obtained from the experimental results of quasi-molecular quenching experiments. It was found that the quenching cross-section increased linearly with the increase of C-H bond number in alkane molecules. As the volume of molecules increases, this increase slows down.