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Appendix A
How the Cary 5000/6000i Controls SBW and Energy
In Double or Double Reverse Beam Mode in the UV/Vis region, (PMT detector), the slit
width (SBW) is used to control the Energy level. In the NIR region (InGaAs detector) the
reverse is normally true—the Energy level controls the SBW. Due to the inherent
differences between the two types of detector, the different methods of control ensure
the widest dynamic range in each region.
If you are collecting data in double beam mode across the UV or UV/Vis regions, with
either Auto or Fixed SBW set as the
Measurement Mode
, you must set a SBW value in
the UV-Vis group. The normal setting is 2.00 nm. You will find that the Energy level will
change automatically to maintain the required signal level.
If you are collecting data in double beam mode across only the NIR region (> the
detector change wavelength, generally 800nm), with either Auto or Fixed Energy set as
the Measurement Mode, you must set an Energy level value in the field in the NIR group.
An Energy setting of 1.0 will provide the best signal-to-noise ratio, but in most cases,
the recommended setting is 3.0. This will provide a smaller SBW over the entire region
and at the detector changeover point, and so the SBW between the NIR region and the
Vis region will be closer. You will find that the SBW will change automatically to
maintain the required signal level.
If you are collecting data in double beam mode across the UV-Vis and NIR regions with
Fixed SBW set as the Measurement Mode then you will need to enter values in the SBW
fields in both the UV-Vis and the NIR group boxes. The values can be the same if you
want to use the same SBW across the whole scan or you can set different values for each
region.
Appendix B:
Acquiring, storing, and retrieving baseline files
The Cary WinUV system collects a new baseline when you select any type of baseline
correction in the Baseline tab of the Setup dialog box and then click the
Baseline
button
in the application window. Depending on the type of correction you have selected, the
Cary will prompt you to perform either one or two baseline scans. The first is always a
100%Tbaseline (with nothing in the beam, or in the case of a Diffuse or Specular
Reflectance measurements, with the 100% reference material in position). The second,
if required, is a 0%Tbaseline (with the sample beam totally blocked so that the
instrument can measure the electronic zero values).
Once the baselines have been collected, they will be automatically applied to each
collected sample data according to the appropriate baseline correction equation. If
there is not a corresponding data point in the current baseline, then the file will be
interpolated to provide the correction. The correction applied to each point is
dependent on the selected baseline type in the Baseline tab.
