Direct measurement of the electrostatic image force of a levitated charged nanoparticle close to a surface

摘要

Short-range forces have important real-world relevance across a range ofsettings in the nano world, from colloids and possibly for protein folding tonano-mechanical devices, but also for detection of weak long-range forces, suchas gravity, at short distances and of candidates to solve the problem of darkenergy. Short-range forces, such as Casimir-Polder or van der Waals are ingeneral difficult to calculate as a consequence of their non-additive nature,and challenging to measure due to their small magnitude - especially forcharged particles where dispersion forces are normally many orders of magnitudesmaller than electrostatic image forces. Therefore short-range forces haverepresented a continuing theoretical and experimental challenge over the lasthalf-century. Here we report on experiments with a single glass nanoparticlelevitated in close proximity to a neutral silicon surface in vacuum, whichallow for direct measurement of short-range forces in a new distance andsensitivity regime - outperforming existing force microscopies.