Hitachi CHROMASTER 5160, Instruction Manual

Page: 537 / 1022

(6) S/N Ratio Calculation for Raman Spectrum of Water
Perform calculation according to the S and N obtained in
the preceding subsections (3) and (5).
(a) Excitation spectrum bandwidth: 15 nm
S/N ratio = S/N (baseline method, S/N ratio
≥ 700)
S/N ratio = S/N (tangent method, S/N ratio ≥ 525)
(b) Emission spectrum bandwidth: 30 nm
S/N ratio = S/N (baseline method, S/N ratio ≥ 900)
Noise value =
Σ
Y
R/n
(Xn shall be determined for
intervals of 0.5 minute)
R=n
R=1
Fig. 4-3 Noise Calculation (extracted from
JAIMAS 0005-1984)
NOTE
: The Raman spectrum of water and the noise level
may be affected by the purity of the water used
and/or the presence of air bubbles.
(7) Measurement of Raman Spectrum of Water Using a Time
Program (when Raman signal intensity obtained in the
preceding subsection (2) is low)
If the sensitivity (S/N ratio of Raman peak of water) is low,
recheck the following items.
(a) When noise is high
(i) Check the distilled water.
* Distilled water should be used soon after its
purification. If left for a long time in a
container made of resin or the like, fluorescent
substance may mix in with the distilled water.
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