分子离子双激发解离通道的竞争

建立了三原子分子离予XYZ＋（XY2^＋）解离产生多种离子产物时Eα和Eβ两个解离通道之间竞争的理论模型．实验测量出碎片产物分支比和对两束解离光光强比的依赖关系后，由理论公式对数据进行拟合获得拟合参数，可以计算出两个激发解离通道α和β的激发截面分支比．

Competition Between Two Excitation-dissociation Channels for Molecular Ions

When the molecular ions XYZ＋ （XY2＋） are excited simultaneously from an electronic state E0 into two higher electronic states Ea and EZ with supervened dissociation or predisso- ciation, competition between the α and β excitation-dissociation channels occurs. A the- oretical model is provided to deal with the competition of the two excitation-dissociation channels with more than two kinds of ionic products for XYZ＋ （XY2＋）. Supposing that the photo-excitation rates of two states Eα and Eβ are much less than their dissociation or pre-dissociation rates, a theoretical equation can be deduced to fit the measured data, which reflects the dependence of the product branching ratios on the intensity ratios of two excitation lasers. From the fitted parameters the excitation cross section ratios are obtained. In experiment, we studied the competition between two excitation-dissociation channels of CO^2＋. By measuring the dependence of the product branching ratio on the intensity ratio of two dissociation lasers and fitting the experiment data with the theoretical equation, excitation cross section ratios were deduced.