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利用离子速度成像方法 ,研究CH2 I2 分子在 2 77— 30 5nm范围内若干波长处的光解离动力学 .通过同一束激光经 (2 +1)共振多光子电离 (REMPI)过程探测光解碎片I(2 P3 2 )和I (2 P1 2 ) ,得到了不同激发波长处的离子速度分布图像 ,从而获得CH2 I2 光解产物的能量分配和角分布 .实验发现 ,碎片CH2 I自由基有很高的内能激发 ,约占总可资用能的 80 %,该能量分配可以较好地用冲击模型来解释 .实验还发现 ,产物I(2 P3 2 )和I (2 P1 2 )具有很不相同的平动能分布 ,结合所得到的碎片能量分配和角分布 ,我们对碎片I(2 P3 2 )和I (2 P1 2 )生成机理进行了分析 ,指出CH2 I2分子电子激发态的绝热和非绝热解离决定了碎片的平动能分布 .
Photodissociation kinetics of CH2 I2 molecules at several wavelengths in the range of 2 77- 30 5 nm were studied using ion-velocity imaging methods Photolysis fragments were detected by the same laser beam through (2 +1) resonant multiphoton ionization (REMPI) I (2 P3 2) and I (2 P1 2), the ion velocity distribution images at different excitation wavelengths were obtained, and the energy distribution and angular distribution of the CH2 I2 photolysis products were obtained. High internal energy excitation, accounting for about 80% of the total available energy, can be better explained by the impact model.The experiments also found that the products I (2 P3 2) and I (2 P1 2) Different from the distribution of translational energy, we have analyzed the formation mechanism of fragment I (2 P3 2) and I (2 P1 2) by combining the energy distribution and angular distribution of the fragments obtained, pointing out that the adiabatic and Non-adiabatic dissociation determines the translational motion of the debris.