Real-time observation of azo-polymer deformation dynamics via high-speed atomic force microscopy

Azo-polymer thin films, containing azo-benzene molecules, form unique surface reliefs due to the photoisomerization reaction under light irradiation, which makes them promising materials for various optical applications. In previous studies, the surface reliefs of azo-polymers have been studied by atomic force microscopy (AFM) after deformation. In this study, we applied high-speed AFM (HS-AFM) for in-situ real-time observation of the deformation dynamics of azopolymer thin films. HS-AFM can capture real-time movies with high spatial and temporal resolutions. We successfully observed the azo-polymer deformation dynamics by HS-AFM under light irradiation with linear polarization. We precisely analyzed the nanoscale temporal evolution of the surface reliefs from the height line-profiles. We further observed an interesting dynamic motion of the azo-polymer film under optical vortex. Through HS-AFM observations under various conditions, the azo-polymer deformation mechanism can be further elucidated.