PDA-100 Photodiode Array Detector
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Doc. 031644-02 9/03
Rise Time
Rise time is a measure of how quickly the PDA-100 responds to a change in
signal. The rise time can be set to 0.1, 0.2, 0.5, 1.0, 2.0 (default), or 5.0 seconds.
The selected rise time is applied to all data collected, and to both analog and
digital output.
Select a rise time that is approximately 25% of the peak width at half-height of the
narrowest peak of interest. A longer rise time allows more averaging of the signal
and results in less short-term noise (see Figure 3-3). However, a rise time that is
too long may result in reduced peak heights and asymmetric peak shapes. When
set correctly, the rise time significantly reduces baseline noise, but reduces peak
height only slightly.
Figure 3-3. Effect of Rise Time on Baseline Noise
-0.0100
0.0000
0.0100
0.0250
0.00
1.00
2.00
3.00
4.00
5.00
mAU
min
WVL:254 nm
-0.0200
-0.0100
0.0000
0.0150
0.00
1.00
2.00
3.00
4.00
5.00
mAU
min
WVL:254 nm
Rise Time: 0.5 sec
Baseline Noise: 22
µ
AU
Rise Time: 2.0 sec
Baseline Noise: 10
µ
AU
