摘要
Plasmonic optical manipulation has emerged as an affordable alternative to manipulate single chemical and biological molecules in nanoscience.Although the theoretical models of sub-5 nm single-molecule trapping have been considered promising,the experimental strategies remain a challenge due to the Brownian motions and weak optical gradient forces with significantly reduced molecular polarizability.Herein,we address direct trapping and in situ sensing of single molecules with unprecedented size,down to∼5Åin solution,by employing an adjustable plasmonic optical nanogap and single-molecule conductance measurement.The theoretical simulations demonstrate that local fields with a high enhancement factor,over 103,were generated at such small nanogaps,resulting in optical forces as large as several piconewtons to suppress the Brownian motion and trap a molecule of length sub-1 nm.This work demonstrates a strategy for directly manipulating the small molecule units,promising a vast multitude of applications in chemical,biological,and materials sciences at the single-molecule level.
基金
supported by the National Natural Science Foundation of China(grant nos.T2222002,21973079,22032004,92161118,12174324,21991130,and 21905238)
the Ministry of Science and Technology of the People’s Republic of China(grant no.2021YFA1201502)
the Natural Science Foundation of Fujian Province(grant no.2021J06008).