3.1 AA-6800/6650 Configurations
3-11
AA-6800/6650 Instruction
3.1.8 Photometric System
Figure 3.9 shows the photometric system.
Figure 3.9 Photometric System
The following five measurement modes can be selected in the AA-6800/6650.
EMISSION mode Used for flame emission analysis.
NON-BGC mode Used for atomic absorption analysis that doesn't require background correction.
BGC-D2 mode Used for atomic absorption analysis that requires background correction.
BGC-SR mode Used for atomic absorption analysis that requires background correction and whose results
are easily affected by nearby spectral lines.
D2 mode Used for background measurement and molecular absorption measurements.
(1) EMISSION mode:
The spectrum produced by atomization of the analysis element in the flame is selected by the
monochromator, and its intensity is measured via photometric circuitry.
(2) NON-BGC mode:
The deuterium lamp is extinguished, and only the light from the hollow cathode lamp, pulsed at 400 Hz, is
passed through the atomizer. Then only the spectral line (analysis line) to be used for analysis by the
monochromator is selected. By measuring the light absorption at this time, it is possible to determine the
concentrations of the elements being analyzed. The detector outputs a signal which is the sum of a 400 Hz
pulsed signal proportional to the analysis line intensity and a direct current signal from the light emitted
from the atomizer (flame or graphite tube).
Lamp power
supply
Hollow cathode
lamp
Burner
Deuterium lamp
Monochromator
Detector
Analog signal processor
Gas control
unit
Half mirror
CPU
PC
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