26
3.4
Adjustment of Instrument
3.4.1
Signal
Noise Ratio Test (Using Raman Spectral Peak of Water)
1
.
..
.
Testing Mode Using a Single Instrument
Make sure the sample cell is empty. First turn on the power switch of the xenon lamp. Check
that the xenon lamp is lit. Then turn on the power switch of the instrument. After starting up, the
instrument will automatically initialize. (The instrument possesses a self-checking function through
a computer and a function of self-correcting wavelength).This process takes about several minutes.
(1) Preheating
After the instrument is started up, the xenon lamp and other electronic components need time to
attain a thermal equilibrium. So measuring operation should be carried out after 30 minutes of
starting up for preheating.
(2) Putting in Sample
Put the sample (redistilled water) into clean quartz sample cell. Hold the sample cell diagonally
with fingers, and place it into the sample cell holder. See Fig.1-4.
Attention: If the quartz sample cell is not clean, it will affect the precision and reduce the S/N.
(3) Wavelength Adjustment
Adjust the value of current wavelength to 415 nm. More detail please turn to 2.3.2.
(4) PMT Level Adjustment
The purpose of PMT level adjustment is to let the displayed value of the sample to be measured
be proper. Adjust the value of fluorescent intensity be between 100 and 200. Find the wavelength
value (
λmax)
of the maximum fluorescent intensity at about 415nm. For more information of
adjustment please turn to 2.3.2.
Then observe for 2 minute at the wavelength
λmax
. Record the values of maximum and
minimum fluorescent intensity, respectively. The sum of the two values is divided by two to give an
average value of fluorescent intensity at wavelength
λmax
. The difference between the two values is
the value of noise at wavelength
λmax
.
After that adjust wavelength to 315nm. The displayed value of fluorescent intensity is the
background value of Raman spectral peak of water. The difference between the above average value
of fluorescent intensity at
λmax
and the background value at 315nm is divided by the value of noise
to give signal noise ratio (S/N) of the instrument.(The product index of the instrument S/N
≥1
50).
Note:
①
In order to protect the photomultiplier, when PMT level is higher (
>
6), please not let high
light pass into the sample compartment.
②
When adjusting PMT level, readjustment of the automatic PMT level system of the
instrument will influence the original set for zero-point of fluorescence. After adjusting PMT level,
please check zero-point. If zero-point changes, it may be adjusted once again.
(5) Shutdown of Instrument
After finishing the test, shut down the instrument. Please turn off the power source of the xenon
lamp first. And then turn off the power source of the Fluorospectrophotometer main unit .
3. Installation of the Instrument
INSTRUCTION MANUAL FOR SPECTRO 96 FLUOROSPECTROPHOTOMETER
