Trapping of Molecules through Stark Effect

由于电磁场与分子之间的相互作用通常很弱，传统的激光冷却和囚禁技术对分子的作用效果不佳。本研究计画的目标是利用静电场或强雷射辐射，发展一种分子的三维捕捉方法。研究结果如下：1.从理论上研究了线性极性分子在四极静电场中的动力学行为及其碰撞过程。经典分析表明，在特定方向上旋转的分子经历朝向场分布中心的恢复力，被三维捕获。捕获寿命制定的马约拉纳过渡。我们还提出了一种用环形电极使分子减速的方法.利用光偶极力捕获饱和溶液中析出的小晶体。已经证明，机械力影响过饱和明矾溶液中晶体生长的动力学，并产生球形多晶体。由于作用在晶体上的梯度力的不同，晶体在空间上按其尺寸分布.采用激光烧蚀分子晶体的方法，在远离共振的光学偶极力阱中产生气态分子。我们的方法是独特的，因为捕获激光器也可以作为烧蚀光源。CO_2激光束的激光电离和激光探测技术正在进行中。

The techniques of conventional laser cooling and trapping are not effective for molecules because the interaction between electromagnetic fields and molecules are usually very weak. The goal of this research project is to develop a 3-dimensional trapping for molecules by use of static electric fields or strong laser radiation. Outcomes of our research are summarized as follows.1. We theoretically investigated dynamics of linear polar molecules in static quadrupole electric fields and their collision process. Classical analysis shows that molecules rotating in a specific direction experience a restoring force toward the center of the field distribution, being 3-dimensionally trapped. The trapping lifetime was formulated in terms of the Majorana transition. We also proposed a method of decelerating molecules with a ring electrode.2. The optical dipole force was used to trap small crystals precipitated from saturated solution. It has been demonstrated that the mechanical force influences dynamics of crystal growth in supersaturated alum solution and produces spherical polycrystals. Precipitated crystals are spatially distributed by their size because of the difference in the gradient force acting on them.3. Laser ablation of molecular crystal was carried out to produce gaseous molecules inside a far-off-resonant optical dipole force trap. Our method is unique in that the trapping laser also works as an ablation light source. The laser ionization and detection of molecules trapped in the focus of CO_2 laser beam are now in progress.