Characterizing and optimizing a laser-desorption molecular beam source
Characterizing and optimizing a laser-desorption molecular beam source
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DOI：
10.1063/1.4991639
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发表时间：
2017-10-14
影响因子：
4.4
通讯作者：
Kuepper, Jochen
中科院分区：
文献类型：
--
作者：
Teschmit, Nicole;Dlugolecki, Karol;Kuepper, Jochen
介绍了一种新型激光解吸分子束源的设计和表征，该源专为 X 射线自由电子激光和超短脉冲激光成像实验而设计。它由一个包含所有源组件的机械单元组成，包括分子束阀、样品和光纤耦合解吸激光器，该激光器可在五个轴上移动，以满足中央设施实验的需要。利用强场电离，我们表征了产生的分子束，并评估了解吸激光脉冲能量、阀门打开和解吸激光的相对时间、样品棒高度以及探测分子包的哪一部分对样品特性的影响。强场电离充当通用探针，可以检测分子束中存在的所有物质，因此使我们能够分析所产生的分子束（包括分子碎片）的纯度。我们提出了用于产生最纯分子束的优化实验参数，其中包含最高产率的完整母离子，我们发现这对超音速膨胀中解吸分子羽流的放置非常敏感。由 AIP 出版社出版。
The design and characterization of a new laser-desorption molecular beam source, tailored for use in x-ray free-electron laser and ultrashort-pulse laser imaging experiments, is presented. It consists of a single mechanical unit containing all source components, including the molecular-beam valve, the sample, and the fiber-coupled desorption laser, which is movable in five axes, as required for experiments at central facilities. Utilizing strong-field ionization, we characterize the produced molecular beam and evaluate the influence of desorption laser pulse energy, relative timing of valve opening and desorption laser, sample bar height, and which part of the molecular packet is probed on the sample properties. Strong-field ionization acts as a universal probe and allows detecting all species present in the molecular beam, and hence enables us to analyze the purity of the produced molecular beam, including molecular fragments. We present optimized experimental parameters for the production of the purest molecular beam, containing the highest yield of intact parent ions, which we find to be very sensitive to the placement of the desorbed-molecule plumes within the supersonic expansion. Published by AIP Publishing.