Thermo Finnigan SpectraSYSTEM UV6000LP, Reference Manual

Page: 81 / 137

January 2004 Thermo Electron 5-5
The Savitsky-Golay bandwidth filter improves the signal-to-noise
ratio, (at the compromise of spectral resolution). The
2
nd
- order Bessel rise time filter reduces short-term noise in the time-
axis with minimal impact on the shape or height of a peak.
In the intensity mode (Figure 5.4) the default controls are slightly
different. The major differences include:
•
No bandwidth or rise time filtering
•
The wavelength units are pixels (diodes 2 to 511)
•
The Y axis units are intensity levels
Figure 5.4 The Control Page - Intensity Mode
There are 512 photodiodes in the detector’s array. The first two
diodes (0 and 1) are not used. Diode 2 is at 190 nm and diode 511 is
at 800 nm when the detector is properly calibrated. This gives a
diode spacing of 611 nm/509 diodes = 1.2 nm/diode. In the
absorbance mode, the detector interpolates between diodes to store
absorbance at integer wavelengths.
Filter Group
The Rise Time field in this group allows you to specify the desired
rise time for the chromatogram plot(s) when the absorbance mode is
selected. To change a displayed value, place the text cursor in the
field and use the backspace or delete key and number keys. The
acceptable values are 0, 0.1, 0.2, 0.5, 1.0, 2.0, 5.0, and 10.0 seconds
where 0 means no filtering.