In Situ Real-Time Observation of Photoinduced Nanoscale Azo-Polymer Motions Using High-Speed Atomic Force Microscopy Combined with an Inverted Optical Microscope

Nano Lett. 2024 Mar 6;24(9):2805-2811. doi: 10.1021/acs.nanolett.3c04877. Epub 2024 Feb 26.

Abstract

High-speed atomic force microscopy (HS-AFM) is an indispensable technique in the field of biology owing to its imaging capability with high spatiotemporal resolution. Furthermore, recent developments established tip-scan stand-alone HS-AFM combined with an optical microscope, drastically improving its versatility. It has considerable potential to contribute to not only biology but also various research fields. A great candidate is a photoactive material, such as an azo-polymer, which is important for optical applications because of its unique nanoscale motion under light irradiation. Here, we demonstrate the in situ observation of nanoscale azo-polymer motion by combining tip-scan HS-AFM with an optical system, allowing HS-AFM observations precisely aligned with a focused laser position. We observed the dynamic evolution of unique morphologies in azo-polymer films. Moreover, real-time topographic line profile analyses facilitated precise investigations of the morphological changes. This important demonstration would pave the way for the application of HS-AFM in a wide range of research fields.

Keywords: azo-polymer; high spatiotemporal resolution; high-speed atomic force microscopy; in situ measurement; nanoscale motion; photoresponsive material.