Raman Imaging

Raman imaging is a powerful technique for generating detailed chemical images based on a sample’s Raman spectrum. A complete spectrum is acquired at each and every pixel of the image, and then interrogated to generate false colour images based on material composition, phase, crystallinity and strain.

In standard operation HORIBA’s confocal Raman microscopes are diffraction limited, with achievable spatial in the order of 250-300nm (depending on laser wavelength and objective) – features smaller than this can still be detected but without true spatial information. Tip Enhanced Raman Spectroscopy (TERS) moves beyond this diffraction limit, allowing a spatial resolution of below 25 nm to be routinely measured on TERS-enabled Raman-AFM systems.

Raman image of graphene
Raman image of graphene, illustrating distribution of monolayer, bilayer and trilayer regions on a silicon substrate.

Standard point-by-point mapping affords the ultimate sensitivity for materials with extremely low Raman scattering properties, and additionally allows high resolution, large spectral range capability. Typical acquisition times for such maps can be in the order of 1s-10s per point (or longer), and thus total measurement times can be significant.

Graphene oxide and single carbon nanotubes on gold, showing nanometer resolution achievable with HORIBA’s commercial TERS systems.

The SWIFT™ Ultra-fast Raman Imaging module offers drastically reduces measurement times with acquisition times down to <5ms/point, allowing large area survey scans, 3D confocal volume mapping and detailed Raman images to be completed in seconds or minutes!

HORIBA Scientific offers a range of novel technologies for Raman imaging:

  • SWIFT™
    Ultra-fast Raman imaging with acquisition times below 5ms/point, allowing hyperspectral Raman images to be acquired in just seconds or minutes!
  • DuoScan™
    The DuoScan™ technology enables the ultimate flexibility for Raman imaging, including easy sub-micron Raman imaging, adjustable laser spot sizes, and 100% coverage of a sample for macro-mapping.
  • EMCCD
    Electron multiplying CCD technology offers significant increases in sensitivity for challenging samples with low signal levels.
Raman image of poly-Silicon showing crystalline, poly-crystalline and nano-crystalline forms.