Infrared scattering scanning near-field optical microscopy using an external cavity quantum cascade laser for nanoscale chemical imaging and spectroscopy of explosive residues

Ian M. Craig, Mark C. Phillips, Matthew S. Taubman, Erik E. Josberger, Markus B. Raschke

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations

Abstract

Infrared scattering scanning near-field optical microscopy (s-SNOM) is an apertureless superfocusing technique that uses the antenna properties of a conducting atomic force microscope (AFM) tip to achieve infrared spatial resolution below the diffraction limit. The instrument can be used either in imaging mode, where a fixed wavelength light source is tuned to a molecular resonance and the AFM raster scans an image, or in spectroscopy mode where the AFM is held stationary over a feature of interest and the light frequency is varied to obtain a spectrum. In either case, a strong, stable, coherent infrared source is required. Here we demonstrate the integration of a broadly tunable external cavity quantum cascade laser (ECQCL) into an s-SNOM and use it to obtain infrared spectra of microcrystals of chemicals adsorbed onto gold substrates. Residues of the explosive compound tetryl was deposited onto gold substrates. s-SNOM experiments were performed in the 1260-1400cm -1 tuning range of the ECQCL, corresponding to the N0 2 symmetric stretch vibrational fingerprint region. Vibrational infrared spectra were collected on individual chemical domains with a collection area of ∼500 nm 2 and compared to ensemble averaged far-field reflection-absorption infrared spectroscopy (RAIRS) results.

Original languageEnglish (US)
Title of host publicationQuantum Sensing and Nanophotonic Devices X
DOIs
StatePublished - 2013
Externally publishedYes
EventQuantum Sensing and Nanophotonic Devices X - San Francisco, CA, United States
Duration: Feb 3 2013Feb 7 2013

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume8631
ISSN (Print)0277-786X

Other

OtherQuantum Sensing and Nanophotonic Devices X
Country/TerritoryUnited States
CitySan Francisco, CA
Period2/3/132/7/13

Keywords

  • AFM
  • chemical imaging
  • ECQCL
  • infrared
  • nano-spectroscopy
  • s-SNOM
  • tetryl

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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