Imaging atomic structures below freezing reveals how molecules behave in cold liquid environments.

Frequency-modulation AFM in sub-zero antifreeze liquid

Atomic force microscopy (AFM) is a powerful tool for topographic imaging and force sensing on solid objects buried in liquid. In the present study, the feasibility of force detection in the frequency-modulation mode has been demonstrated in 1-octanol liquid at temperatures as low as −15 °C. A commercial microscope was cooled within an acoustic enclosure, and topographic images of octanol molecules adsorbed on graphite were obtained with nanometer-scale resolution. The molecules of octanol in the liquid phase exhibited flat layers over the octanol-adsorbed graphite, as evidenced by a series of force–distance curves. This research certified the usability of frequency-modulation AFM operated at sub-zero temperatures, even though the viscosity of the imaging liquid is enhanced.