nano-FTIR (nanoscale FTIR) is a powerful combination of s-SNOM equipped with broadband illumination and FTIR-based detection developed by neaspec. nano-FTIR provides infrared spectroscopy at the spatial resolution of AFM, delivering nanoscale chemical identification and hyperspectral imaging.
Basic Working Principle:
- focus broadband IR beam onto a sharp AFM tip;
- illuminated tip creates a strong nano-focus at its apex;
- nano-focus acts as a ultra-small “white light” source that probes spectral properties of a sample through near-field optical interaction, which modifies tip-scattered light.
- FTIR detection recovers both amplitude and phase of the tip-scattered light, delivering complete spectral response of the sample (e.g. both absorption and reflectivity).
Challenge: Broadband illumination requires a method for recording spectrally-resolved amplitude (reflectivity) and phase (absorption) of the broadband scattered light, while completely suppressing parasitic background. A strong light source with large spectral bandwidth is also needed to achieve nano-FTIR spectroscopy with sufficient spectral coverage in a single shot.
nano-FTIR was developed and patented by neaspec and is the only technology that can simultaneously detect broadband near-field amplitude and phase spectra with 100% background suppression.
nano-FTIR is based in on a s-SNOM setup comprising an asymmetric interferometer where the AFM tip and the sample are located in one of the interferometer arms. Broadband source (e.g. laser, synchrotron, etc.) illuminates the AFM tip. Tip-scattered light is recombined with the reference beam at the detector. The detector signal is recorded as a function of reference mirror position, creating an (asymmetric) interferogram. Fourier transformation of this interferogram returns the local amplitude and phase spectra, which relate to the sample reflectivity and absorption.
List of other neaspec’s patented s-SNOM detection technologies that provide 100% background suppression:
- PsHet (Pseudo-Heterodyne): golden standard for nanoscale imaging and spectroscopy.
- P-Spec: PsHet-quality s-SNOM point spectroscopy by laser sweeping.
- HSH (High-Speed Holography): fastest imaging method for screening of large sample areas with the best S/N quality of all known s-SNOM imaging methods.
The only successful nano-spectroscopy proven to work with synchrotron radiation