Advanced Infrared Nanospectroscopy Using Photothermal Induced Resonance Technique, AFMIR: New Approach Using Tapping Mode

For 10 years, a new instrumentation, called AFM-IR, has been developed in our team to perform IR analyses at the nanoscale. This technique is based on photothermal effect and is the result of a coupling between atomic force microscopy and IR spectroscopy to perform local IR absorption measurements. This combination makes it possible to identify at the nanoscale organic molecules without using exogenous markers. Nevertheless, in its initial configuration, the instrumentation has reached limits. New experimental approaches are therefore developed to solve the problems and overcome the technical constraints imposed by the system itself. In particular, two changes were significant: first, a change of configuration was done that allowed us to go down in terms of resolution and to reach tens of nanometers. The second concerned the AFM imaging itself: AFM-IR was used mainly in the contact mode, thus preventing its application in soft or loosely adhered. Here, we will describe this new mode which enabled addressing the limitations of the contact mode AFM-IR.