Hitachi PRIMAIDE 1440 Instruction Manual page 124

(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 =  Y
Fig. 4-3 Noise Calculation (extracted from
JAIMAS 0005-2005)
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
4 - 11
R=n
(Xn shall be determined for
R/n
R=1
intervals of 0.5 minute)