Atomic force microscopy at low temperatures
A cryogenic environment can dramatically increase the Q factor (quality factor) of an atomic force microscope (AFM).
A high Q factor leads to better image resolution and higher sensitivity. It reduces the risk for damage on the sample and AFM tip. On the other hand, the resonator properties (amplitude, phase, resonant frequency) change in both size and polarity. Additionally, problems may occur during the measurement. While an increased sensitivity may seem desirable, aspects that under certain environmental conditions disappear in the noise can be dangerous at low temperatures. For example, at low temperatures the intrinsic attenuation of the AFM tip is smaller than at higher temperatures, which leads to higher sensitivity of the tip in regards to interactions with the sample surface. This results in better resolution in z direction, as smaller force gradients can be detected. This topic is treated in great detail in a white paper by Ryan Murdick, a well-known expert in the field of AFM technology. Since 2017, Ryan Murdick has been contributing his expertise as Product Development Scientist at Montana Instruments. The full white paper can be found at this link: http://downloads.montanainstruments.com/cryogenic_afm/