Photoinduced force microscopy: A technique for hyperspectral nanochemical mapping

Abstract

Advances in nanotechnology have intensified the need for tools that can characterize newly synthesized nanomaterials. A variety of techniques has recently been shown which combines atomic force microscopy (AFM) with optical illumination including tip-enhanced Raman spectroscopy (TERS), scattering-type scanning near-field optical microscopy (sSNOM), and photothermal induced resonance microscopy (PTIR). To varying degrees, these existing techniques enable optical spectroscopy with the nanoscale spatial resolution inherent to AFM, thereby providing nanochemical interrogation of a specimen. Here we discuss photoinduced force microscopy (PiFM), a recently developed technique for nanoscale optical spectroscopy that exploits image forces acting between an AFM tip and sample to detect wavelength-dependent polarization within the sample to generate absorption spectra. This approach enables ∼10 nm spatial resolution with spectra that show correlation with macroscopic optical absorption spectra. Unlike other techniques, PiFM achieves this high resolution with virtually no constraints on sample or substrate properties. The applicability of PiFM to a variety of archetypal systems is reported here, highlighting the potential of PiFM as a useful tool for a wide variety of industrial and academic investigations, including semiconducting nanoparticles, nanocellulose, block copolymers, and low dimensional systems, as well as chemical and morphological mixing at interfaces.

Advanced Characterization Methods for Electrical and Sensoric Components and Devices at the Micro and Nano Scales

“…If visible light is used, it is referred to as nano‐Vis (cf. Figure ), while the umbrella term is PTIR . Closely related, using the same excitation scheme but modified probes, scanning thermal microscopy (SThM) reveals the local temperature of the sample.…”

“…Section ) and TERS (cf. Section ), PTIR microscopy was created as a technique to allow a nano(photo)chemical detection of samples …”

“…A noncontact variation of nanoscale spectral recording is photo‐induced force microscopy (PIFM) . It uses AFM to measure the dipole–dipole force gradients occurring between the sample and the metalized tip as wavelength‐dependent polarization and transform them into an absorption spectrum resolving molecular vibrational resonances .…”

Functional Scanning Force Microscopy for Energy Nanodevices

“…Scanning‐probe‐based nanometer‐scaled infrared spectroscopy (nano‐IR), which combines the high spatial resolution of AFM with the chemical analysis ability of IR spectroscopy, has been achieved and increasingly utilized in energy nanodevice research. Three techniques are developed for this purpose, namely photothermal induced resonance (PTIR), photoinduced force microscopy (PiFM) and infrared apertureless near‐field scanning optical microscopy (IR‐aNSOM) . All of them require focused tunable IR laser incident on sample precisely positioned under scanning tip apex.…”

Nanoscale infrared imaging of zeolites using photoinduced force microscopy

“…1). 16,17 Herein, the incorporation and spatial distribution of framework Al 3+ into zeolite ZSM-5 thin-films have been studied using PiFM, and nanometer scale structureperformance relationships have been established by mapping the surface of the zeolite thin-film (Si/Al = 45) after the methanol-to-hydrocarbons (MTH) reaction.…”