PerkinElmer RamanFlex 400, Getting Started Manual

Page: 67 / 94

Introduction to the RamanFlex 400 . 67
Non Immersion
When using 785 nm lasers, many types of glass exhibit fluorescent bands between 1400–
1600 cm
−1
. Glass spectra of the container should be obtained before analyzing the sample to
ensure that glass-derived fluorescence bands do not pose a problem. With 785 nm
excitation, fused silica (quartz) should be used instead of glass where possible as this does
not yield fluorescent peaks. Pyrex is also excellent for Raman analysis. When working
through containers it is best to try different probe positions. If the liquid of interest is not
absorbing it may be best to focus through the container by placing the FOP in contact with
the container.
If this glass fluorescence is a problem and it is not possible to use quartz containers, then it
is possible to acquire a spectrum of the container, and spectrally subtract this from any
spectra containing this fluorescent signature.
Sampling Slurries / Highly absorbing species
Please refer to
Sampling Liquids
. For sample immersion care taken in focusing the probe
within the sleeve can result in a dramatic improvement in spectral quality.
Gas Sampling
Although Raman scattering from gas samples is very weak, the FOP can be used to measure
gas phase under long acquisition times.
WARNING
The standard FOP is not designed for immersion use. The FOP is
sealed against minor splashes, however, immersion in solvents will
cause serious damage. Ensure an immersion sleeve is in place before
immersing your FOP; see Figure 16. Please contact PerkinElmer if you
have any questions in relation to sampling using the FOP.