What is remote in situ Raman analysis?

As its name suggests remote in situ Raman analysis is a method of analysing a sample in situ and/or in a remote location, rather than having to extract some of the sample and take it to a Raman spectrometer.  It is often used in industrial settings, where examples include monitoring of reaction components in a reaction vessel (from a small glass flask through to industrial scale reactors), and analysis of chemicals at multiple positions in pipe lines.

Remote in situ Raman is often carried out using optical fibres, allowing a Raman probe head to be coupled to a spectrometer (which can be many hundreds of meters away from the analysis point).   A single cable is used to transmit the laser to the sample, whilst another fibre is then used to transfer the Raman signal from the sample to a standard spectrometer and detection system.  These two cables are connected to a compact, rugged Raman probe head which focuses the laser onto the sample, and collects the Raman signal.

The probes are suitable for use at high temperatures and pressures.  They can operate in either an immersion mode (where the analysis head is dipped within the reaction liquid) or in a stand-off mode (where the analysis is made by focusing the laser through a transparent window in the reaction vessel or pipeline).

In situ Raman analysis can be used for:

  • Solution/reaction mixes
  • Emulsions
  • Slurry and suspensions
  • Headspace in vials/reactors
  • Raw and bulk material feeds
  • Vessel cleaning effluents
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