Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
J Chem Phys. 2013 May 28;138(20):204311. doi: 10.1063/1.4804653.
We have made a series of measurements, as a function of pulse duration, of ionization and fragmentation of the asymmetric molecule N2O in intense femtosecond laser radiation. The pulse length was varied from 7 fs to 500 fs with intensity ranging from 4 × 10(15) to 2.5 × 10(14) W∕cm(2). Time and position sensitive detection allows us to observe all fragments in coincidence. By representing the final dissociation geometry with Dalitz plots, we can identify the underlying breakup dynamics. We observe for the first time that there are two stepwise dissociation pathways for N2O(3+): (1) N2O(3+) → N(+) + NO(2+) → N(+) + N(+) + O(+) and (2) N2O(3+) → N2 (2+) + O(+) → N(+) + N(+) + O(+) as well as one for N2O(4+) → N(2+) + NO(2+) → N(2+) + N(+) + O(+). The N2 (2+) stepwise channel is suppressed for longer pulse length, a phenomenon which we attribute to the influence which the structure of the 3+ potential has on the dissociating wave packet propagation. Finally, by observing the total kinetic energy released for each channel as a function of pulse duration, we show the increasing importance of charge resonance enhanced ionization for channels higher than 3+.
我们已经进行了一系列的测量，作为一个函数的脉冲持续时间，电离和断裂的非对称分子 N2O 在强烈的飞秒激光辐射。脉冲长度从 7 fs 到 500 fs 变化，强度范围从 4 × 10(15)到 2.5 × 10(14) W∕cm(2)。时间和位置敏感检测允许我们观察到所有的碎片在巧合。通过表示最终的解离几何 Dalitz 图，我们可以识别潜在的分裂动力学。我们首次观察到有两个逐步解离途径的 N2O(3+)：(1) N2O(3+)→N(+) + NO(2+)→N(+) + N(+) + O(+)和(2) N2O(3+)→N2 (2+) + O(+)→N(+) + N(+) + O(+)以及一个 N2O(4+)→N(2+) + NO(2+)→N(2+) + N(+) + O(+)。N2 (2+)逐步通道是抑制更长的脉冲长度，这种现象我们归因于结构的影响 3+潜在的对解离波包传播。最后，通过观察总动能释放的每个通道的脉冲持续时间，我们显示了电荷共振增强电离通道的重要性增加高于 3+。
