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comehappyon

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[交流] 荧光分析

"Figure 2.30 shows the time-resolved luminescence of Eu2+-doped Sr2Si5N8 measured at varying delay times."
我在文献中看到的这段话，我做的是荧光粉，然后不明白，在荧光分析中为什么要测delay time？

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1楼 2011-11-30 14:32:07

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padodo

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comehappyon(金币+1): delay time貌似是衰减时间，但是具体有什么理论方面的理解么？ 2011-11-30 15:03:14

应该是发光强度会随时间而变化，delay time即指放置的时间

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2楼2011-11-30 14:42:40

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chaijudi

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comehappyon(金币+2): 这个太抽象了，实在看不明白。 2011-12-01 08:46:13

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1楼: Originally posted by comehappyon at 2011-11-30 14:32:07:
"Figure 2.30 shows the time-resolved luminescence of Eu2+-doped Sr2Si5N8 measured at varying delay times."
我在文献中看到的这段话，我做的是荧光粉，然后不明白，在荧光分析中为什么 ...

Delay Lines
Delay lines, or a way to introduce time delays, are incorporated
into all TCSPC instruments. The need for delay lines
is easily understood by recognizing that there are significant
time delays in all components of the instrument. A
photoelectron pulse may take 20 ns to exit a PMT. Electrical
signals in a cable travel a foot in about 1 ns. It would be
difficult to match all these delays within a couple of
nanoseconds in the start and stop detector channels without
a way to adjust the delays. The need for matching delays
through the components is avoided by the use of calibrated
delay lines. Such delays are part of the NIM bin electronics.
However, lengths of coaxial cable are prone to picking up
RF interference.
Calibrated delay lines are also useful for calibration of
the time axis of the MCA. This is accomplished by providing
the same input signal to the start and stop channels of
the TAC. The preferred approach is to split an electrical signal,
typically from the start detector, and direct this signal
to both inputs of the TAC. Since the pulses arrive with a
constant time difference, one observes a single peak in the
MCA. One then switches the time delay in the start or stop
channel by a known amount, and finds the peak shift on the
MCA display. By repeating this process for several delay
times, the TAC and MCA can be calibrated.

自己多看几次，估计能看明白

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3楼2011-11-30 15:47:43

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