Photo induced force microscopy: chemical spectroscopy beyond the diffraction limit

Over the last decade remarkable advances have been made in creating spectroscopic tools to interrogate surface properties using electromagnetic radiation in the near field, achieving lateral resolutions in the nanometre range. We review recent work involving one of the most promising of these spectroscopic tools, photo induced force microscopy (PiFM), which uses mechanical detection of dipole-dipole interactions enabling nanometre resolved mapping of surface properties ranging from vibrational modes of adsorbates to plasmon resonances. We discuss the origin of contrast in PiFM images, its applications as a local probe of chemical species and for mapping local electric fields in areas as diverse as zeolite films and biometric recognition. In comparison with related techniques such as photothermal atomic force microscopy-based infrared (AFM-IR) and tip enhanced Raman spectroscopy (TERS) PiFM has many advantages but perhaps its most successful application is in combination with other surface characterisation methods which provide information averaged over much greater surface areas. We discuss the most recent developments of PiFM technology which are leading to higher resolution images and are widening the range of environments in which the technique can be applied, and we consider how the field is likely to progress in the future.

Automated summary

This article reviews the remarkable advances made in the past decade in using spectroscopic tools to study surface properties. It focuses on the use of photo induced force microscopy (PiFM) as a promising tool, which enables nanometer-resolved mapping of surface properties. PiFM utilizes mechanical detection of dipole-dipole interactions to achieve high resolution imaging of surface properties, including vibrational modes of adsorbates and plasmon resonances. Compared to other related techniques, PiFM has many advantages, especially when combined with other surface characterization methods. The future of PiFM technology is likely to involve higher resolution imaging and wider application in different environments.