Post extraction inversion slice imaging for 3D velocity map imaging experiments
Post extraction inversion slice imaging for 3D velocity map imaging experiments
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DOI：
10.1080/00268976.2020.1842531
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发表时间：
2020-11-05
影响因子：
1.7
通讯作者：
Brouard, Mark
中科院分区：
文献类型：
--
作者：
Allum, Felix;Mason, Robert;Brouard, Mark
提出了一种用于速度图离子成像实验的实验结构，在该结构中，脉冲电压使离子牛顿球沿飞行时间轴散焦。这大大扩展了具有相同质量电荷比的离子的飞行时间，允许沿飞行时间轴以高切片分辨率进行切片或三维速度成像。该技术与事件触发的位置敏感传感器相结合，实现了高计数率下的全三维牛顿球体成像，与以前的DC切片方法相比，切片分辨率显著提高(类似于1-2%)。在相对较高的提取电压下可以获得良好的切片成像条件，从而避免了在低提取电压下操作时有关图像大小、杂散场和低检测效率的问题。该方法被称为后提取反转切片成像(PEISI)，通过离子轨迹模拟进行了优化，并在230 nm左右的OCS的光解离实验中得到了实验验证。我们证明，这种方法适合于记录在探测器平面上缺乏柱对称轴的系统的全三维角分布，其中传统的图像反演技术是无效的。这种方法可以用于一系列缺乏柱状对称性的系统，包括角动量极化和双分子散射的研究。
An experimental configuration for velocity map ion imaging experiments is presented, in which a pulsed voltage defocusses the ion Newton sphere along the time-of-flight axis. This significantly spreads the times-of-flight for ions with the same mass-to-charge ratio, allowing for either sliced or three-dimensional velocity imaging with high slicing resolution along the time-of-flight axis. The technique is coupled to an event-triggered, position-sensitive sensor, enabling full three-dimensional Newton sphere imaging at high count rates, with significantly improved slicing resolution (similar to 1-2%) compared to previous DC slicing approaches. Good slice imaging conditions can be brought about at relatively high extraction voltages, circumventing issues regarding image size, stray fields, and poor detection efficiency when operating at low extraction voltages. The method, termed Post Extraction Inversion Slice Imaging (PEISI) was optimised through ion trajectory simulations and experimentally verified on the well-studied photodissociation of OCS at around 230 nm. We demonstrate that this approach is suitable for recording full 3D angular distributions of systems lacking an axis of cylindrical symmetry in the detector plane, where conventional image inversion techniques are invalid. This method could be useful in a range of systems lacking cylindrical symmetry, including studies into angular momentum polarisation and bimolecular scattering.