Graneek Jack B, Merz Simon, Patterson David, Betz Thomas, Schnell Melanie
Max-Planck-Institut für Struktur und Dynamik der Materie, at the Center for Free-Electron Laser Science, Luruper Chaussee 149, 22761, Hamburg, Germany.
Harvard University, Department of Physics, 17 Oxford St, Cambridge, MA, USA.
Chemphyschem. 2016 Nov 18;17(22):3624-3630. doi: 10.1002/cphc.201600538. Epub 2016 Sep 26.
A numerical approach that employs a multi-level dressed state method to determine the AC-Stark shifts of molecular rotational energy levels is described. This approach goes beyond the two-level approximation often employed for simpler molecules, such as ammonia and acetonitrile, and is applicable to a variety of molecules. The calculations are used to develop experiments aimed at focusing, guiding, decelerating and trapping neutral, polyatomic, asymmetric-top molecules by using microwave fields. Herein, numerical calculations are performed for acetonitrile and 4-aminobenzonitrile. Based on these results, trajectory simulations are performed to predict the outcome of microwave focusing experiments in the TE mode of a cylindrically symmetric microwave resonator. Simulations show that, for such an experimental setup, microwave focusing and guiding of 4-aminobenzonitrile requires starting longitudinal velocities close to, or below, 100 m s , that is, much lower than values obtained with standard molecular beam techniques, such as supersonic expansion. Therefore, alternative beam-generation techniques, for example, buffer-gas-cooled molecular beams, are required to extend microwave manipulation methods to larger and more complex molecules.
描述了一种采用多能级缀饰态方法来确定分子转动能级交流斯塔克位移的数值方法。这种方法超越了通常用于诸如氨和乙腈等较简单分子的两能级近似，适用于多种分子。这些计算用于开展旨在通过微波场对中性、多原子、非对称陀螺分子进行聚焦、引导、减速和俘获的实验。在此，对乙腈和4-氨基苯腈进行了数值计算。基于这些结果，进行了轨迹模拟以预测在圆柱对称微波谐振器的TE模式下微波聚焦实验的结果。模拟表明，对于这样的实验装置，4-氨基苯腈的微波聚焦和引导要求起始纵向速度接近或低于100 m/s，即远低于通过标准分子束技术（如超声速膨胀）获得的值。因此，需要替代的束流产生技术，例如缓冲气体冷却分子束，以将微波操纵方法扩展到更大和更复杂的分子。
