Circularly polarized light (CPL) exerts a force of different magnitude on left- and right-handed enantiomers, an effect that could be exploited for chiral resolution of chemical compounds^1,2,3,4,5 as well as controlled assembly of chiral nanostructures^6,7. However, enantioselective optical forces are challenging to control and quantify because their magnitude is extremely small (sub-piconewton) and varies in space with sub-micrometre resolution². Here, we report a technique to both strengthen and visualize these forces, using a chiral atomic force microscope probe coupled to a plasmonic optical tweezer^{8,9,10,11,12,13}. Illumination of the plasmonic tweezer with CPL exerts a force on the microscope tip that depends on the handedness of the light and the tip. In particular, for a left-handed chiral tip, transverse forces are attractive with left-CPL and repulsive with right-CPL. Additionally, total force differences between opposite-handed specimens exceed 10 pN. The microscope tip can map chiral forces with 2 nm lateral resolution, revealing a distinct spatial distribution of forces for each handedness.

圆偏振光 (CPL) 对左手和右手对映异构体施加不同大小的力，这种效应可用于化合物^{1、2、3、4、5}的手性拆分以及手性纳米结构的受控组装^6,7。然而，对映选择性光学力难以控制和量化，因为它们的量级非常小（亚皮牛顿），并且在空间中以亚微米分辨率²变化。在这里，我们报告了一种增强和可视化这些力的技术，使用与等离子体光学镊子耦合的手性原子力显微镜探针^{8,9,10,11,12,13}. 用 CPL 照明等离子镊子会对显微镜尖端施加一个力，这取决于光和尖端的手性。特别是，对于左手手征尖端，横向力对左 CPL 有吸引力，而对右 CPL 排斥。此外，反手试样之间的总力差超过 10 pN。显微镜尖端可以绘制具有 2 nm 横向分辨率的手性力，揭示每个手性的不同空间分布。