2: Set-up and Operation
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15
Wavenumbers
Dynamic Raman Scattering (DRS)
DRS
is a spectroscopic technique developed to enhance spectra produced by free floating particles in
solution. The feature is available both on the system’s firmware and in Peak software.
DRS measures the extra noise created when particles move in and out of the laser beam used to create the
spectrum. This technique was developed by Scott and Carron
1
to remove the interfering background from
material surrounding the moving particles and the container material.
The principle of DRS is that the solvent matrix surrounding small free floating particles is constant and
the container material is also constant. However, the spectrum produced by a low concentration of
particles will exhibit large fluctuations due to their movement in and out of the laser beam.
Button
Function
DRS
When this button is pressed the software pops up a control for the number of spectra
to acquire. When the
DRS
button is released the IDRaman mini acquires and
displays the number of spectra chosen. DRS will produce optimal results with short
integration times and statistically most significant with a relatively large number of
acquisitions.
When the acquisitions are completed the DRS spectrum will be displayed.
Saving Spectra
You can choose to save spectra in one of three formats:
•
GRAMS.spc – The .spc format used with Thermo Scientific GRAMS software.
•
ASCII.prn – This format saves your spectra in a column of wavenumbers and a column of
intensities. See the figure below of an example ASCII format.
•
Lib File.lib – This is a compressed format of library files. Choosing this option stores your
spectra in a format that can be added to the IDRaman mini library. In the autonomous mode the
IDRaman mini automatically performs a clean; it is recommended that you store clean spectra
when creating library files.
►
Procedure
If you choose to save your spectrum in the .spc format,
1.
Select GRAMS.spc in the dialog widow and press the
Save
button a second time. A comment line
will appear.
2.
Add comments then press
Enter
. A file dialog will open to save your spectrum in the .spc format
used with Thermo Scientific GRAMS. This format saves your integration time and number of
averages.