非共振激光与分子的相互作用引起的光偶极力是一种适用于一切分子的控制分子外部自由度的手段，比起斯塔克折射器或六极杆聚焦器等装置具有普遍性，应用在分子束中分子的聚焦、减速、分离等等。目前用来进行分子分离的由单束聚焦激光场构成的分子棱镜只能在速度空间进行分离，而且分子折射效率比较低。两束相向干涉的激光形成光驻波，其激光强度梯度远大于单束聚焦激光的强度梯度，而且光偶极力正比于激光强度梯度和分子的极化率，因此光驻波的分子折射效率高，而且分子之间因不同的极化率其被折射程度不同。本研究拟利用这种光驻波形成的高效光偶极力，开发一种以极化率与分子质量之比在空间上分离分子束中分子的新型方法，并且利用到分子振动态选择。具体研究过程中，我们将详细分析分子束中不同分子被光驻波折射程度的差异，还将分析非线性过程对光偶极力的影响。

The optical dipole force exerted to a molecule by a nonresonant laser field is a universal tool for controlling molecular external degrees of freedom, which leads to various applications such as molecule focusing, slowing, and separation. The molecular prism used in molecular separation have some problems like low deflection efficiency and limitation of doing spatial separation. The optical dipole force is proportional to the molecular polarizability and field gradient and thus can be improved by increasing the field gradient. A high efficient molecular disperser was developed by employing an optical standing wave composed of two counter-propagating laser beams. We found that the molecular deflection is positively correlated to the polarizability-to-mass ratio. We here propose a method of application of the enhanced optical dipole force using an optical standing wave to molecular spatial separation with respect to the effective polarizability-to-mass ratios. This method will be applied to the molecular vibrational state selection. Furthermore, the effect of a nonlinear process to the optical dipole force will be investigated.