BUCHI NIRWare - Manual (Page 134)

128

Tutorial NIRWare 1.5 Software Manual
In order to change the wavenumber range first changes the number of datapoints. Using an interval of 4
cm
-1
and starting at 4,000cm
-1
the upper limit will be reached at 10,000cm
-1
using 1,501 datapoints
(default) and at 12,200cm
-1
using 2051 datapoints.
For Solids Transmittance an interval of 4 cm
-1
and starting wavenumber at 6,000cm
-1
is used. The default
number of datapoints is 1,381 (11,520-6,000 cm
-1
). The upper limit will be reached with 1,551 datapoints
(12,200-6,000 cm
-1
).
It is also possible to change the lower wavenumber limit. However the intensity will drop dramatically
below 4,000 cm
-1
(6,000 cm
-1
for Solids Transmittance). Therefore we do not recommend doing so.
5.12.2. Limitations, Risks and Warnings

The NIRFlex N-500 has been designed for a spectral range of 10.000 – 4.000 cm -1
.
Therefore all optical components are laid out according to this specification. The overall
performance of the NIRFlex N-500 is decreasing for shorter wavelengths. Source, detector
coatings and interferometer all contribute to this effect.

The lower limit is defined by the cut-off of the extended range InGaAs detector and the
intensity drops very much below 4.000 cm
-1
. Therefore the reproducibility will decrease in this
range.

Therefore in the extended range the NIRFlex N-500 will not be as stable as it is in the
specified range and data transfer will be more problematic, because each individual system
may behave differently in that range.