FluoroMax-3 v. 3.1 (3 Mar 2006)
Optimizing Data
5-9
Note:
This table is only a
guide
. The optimum integration time for other
measurements, such as time-base, polarization, phosphorescence
lifetimes, and anisotropy, may be different.
Determining the optimum integration time
The length of time during which photons are counted and averaged for each data point
is referred to as the
integration time
. An unwanted portion of this signal comes from
noise and dark counts (distortion inherent in the signal detector and its electronics when
high voltage is applied). By increasing the integration time, the signal is averaged
longer, resulting in a better
S
/
N
. This ratio is enhanced by a factor of
t
1/2
, where
t
is the
multiplicative increase in integration time. For example, doubling the integration time
from 1 s to 2 s increases the
S
/
N
by over 40%, as shown below:
For an integration time of 1 second,
S N
t
/
/
/
=
=
=
1 2
1 2
1
1
For an integration time of 2 seconds,
S N
t
/
.
/
/
=
=
≈
1 2
1 2
2
1414
or approximately 42%. Because
S
/
N
determines the noise level in a spectrum, use of the
appropriate integration time is important for high-quality results.
To discover the appropriate integration time:
a
Find the maximum fluorescence intensity by acquiring a preliminary scan, using
an integration time of 0.1 s and a bandpass of 5 nm.
b
From this preliminary scan, note the maximum intensity, and select the appro-
priate integration time from the table below.
Signal intensity
(counts per second)
Estimated integration time
(seconds)
1000 to 5000
2.0
5001 to 50 000
1.0
50 001 to 500 000
0.1
500 001 to 4 000 000
0.05
Set integration time through
Experiment Setup
for a specific experiment, or
Real Time
Control
to view the effects of different integration times on a spectrum. See the Fluo-
rEssence™ on-line help to learn more about setting the integration time.
Содержание FluoroMax-3
Страница 5: ...FluoroMax 3 v 3 1 3 Mar 2006 v 15 Declaration of Conformity 15 1 16 Index 16 1...
Страница 6: ...FluoroMax 3 v 3 1 3 Mar 2006 vi...
Страница 18: ...FluoroMax 3 v 3 1 3 Mar 2006 Introduction 0 12...
Страница 36: ...FluoroMax 3 v 3 22 Feb 2005 System Description 2 8...
Страница 96: ...FluoroMax 3 v 3 1 3 Mar 2006 Maintenance 6 12...
Страница 156: ...FluoroMax 3 v 3 1 6 Mar 2006 Automated Polarizers 10 22...
Страница 208: ...FluoroMax 3 v 3 1 6 Mar 2006 Bibliography 14 4...
Страница 210: ...FluoroMax 3 v 3 1 6 Mar 2006 Declaration of Conformity 15 2...
Страница 220: ...FluoroMax 3 v 3 1 25 Apr 2006 Index 16 10...
